Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsapm.3c00031

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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

(Diamine)Pd(0)(dichlone)/NaBPh₄ systems have been revealed to be effective initiators for diazoacetate polymerization, yielding moderately syndiotactic polymers in moderate yields.

DOI： 10.1039/d2py01548j

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Publishing type：Research paper (scientific journal)  

Dispersion polymerization stabilized with poly(acrylic acid) has been performed for decades to produce polymer particles whose surfaces are modified with pH-responsive poly(acrylic acid) moieties. To improve stabilizer efficiency, poly(acrylic acid) block copolymers, in which a poly(acrylic acid) chain is attached to the terminus of a polystyrene or PMMA chain, were used as stabilizers for the dispersion polymerization of styrene or MMA. Compared with the poly(acrylic acid) homopolymer, polystyrene-block-poly(acrylic acid) was found to improve the controllable ranges of particle size and the carboxylic-acid-group surface density of the resulting polystyrene particles. Furthermore, we also investigated the effect of heterogeneity between the polymer species of the particle core and the attached polystyrene or PMMA chains in the poly(acrylic acid) block copolymers. Finally, we also examined the applicability of polystyrene-block-poly(acrylic acid) as a stabilizer and surface modifier for the dispersion polymerization of various monomers.

DOI： 10.1016/j.polymer.2022.125265

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

Three new N-arylmaleimide-based Pd(0) complexes [Pd(N-phenylmaleimide)2(2,5-norbornadiene) (1), Pd(N-2,6-difluorophenylmaleimide)2(2,5-norbornadiene) (2), and Pd(N-2,6-difluorophenylmaleimide)2(dibenzylideneacetone) (3)] were prepared and used as an initiator in conjunction with NaBPh4[Pd(N-arylmaleimide)/NaBPh4system] for polymerization of diazoacetates. The Pd(N-arylmaleimide)/NaBPh4system polymerized a series of diazoacetates (ethyl, benzyl, and cyclohexyl diazoacetates) to yield polymers in moderate to good yield, particularly showing a high activity for cyclohexyl diazoacetate. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis and other experimental observations revealed the incorporation of one N-arylmaleimide molecule coordinated on the Pd center into the α-chain end of the polymers obtained with the initiating system, indicating that the initiating species of the polymerization was generated by insertion of N-arylmaleimide into a Pd-Ph linkage, which was first formed by the reaction of the Pd(0) complex with NaBPh4, and that the initiating system would enable syntheses of α-chain-end-functionalized poly(alkoxycarbonylmethylene)s.

DOI： 10.1021/acs.macromol.2c00508

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

Polycondensation of a bis(diazocarbonyl) compound and diaminotriphenylamine derivatization via Ru-catalyzed N–H insertion to afford electroactive polyamine.

DOI： 10.1039/d2py01118b

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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

<p>The reactivities of poly(alkoxycarbonylmethylene)s under basic conditions are described. The reactions of poly(ethoxycarbonylmethylene) (<bold>polyEDA’</bold>) and poly(benzyloxycarbonylmethylene) (<bold>polyBDA’</bold>) with a mixture of lithium diisopropylamide and trimethylsilyl chloride transformed a part of...</p>

DOI： 10.1039/d0py01486a

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.macromol.0c01029

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsapm.0c00475

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

In the polymerization of diazoacetates initiated by pi-allylPd-based initiating systems, the effects of solvents, additives, and pi-allyl ligand structures on the polymerization behavior were investigated. As a result, the polymerization in the presence of pyridine or its derivatives as an additive was found to afford a polymer with relatively narrow molecular weight distribution compared to that with pi-allylPdCl alone. Furthermore, we have demonstrated that Pd complexes with pi-allyl ligands with a variety of substituents are capable of polymerizing diazoacetates in a similar manner to the parent unsubstituted pi-allylPdCl, and the tacticity of the resulting polymers is affected by the structure of the pi-allyl ligands.

DOI： 10.1039/c9py01654f

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Publishing type：Research paper (scientific journal)  

© 2019, The Society of Polymer Science, Japan. The synthesis and characterization of organic-inorganic thermoresponsive poly(substituted methylene)s are described. Diazoacetates with oligo(ethylene glycol)-substituted cyclotriphosphazenes were synthesized, and the obtained products were employed as monomers for Pd-initiated polymerization to produce carbon–carbon main chain polymers bearing an oligo(ethylene glycol)-substituted cyclotriphosphazene on every main chain carbon atom. The resulting polymers with densely accumulated oligo(ethylene glycol) units around the polymer main chain showed lower critical solution temperature-type phase separation in an aqueous medium.

DOI： 10.1038/s41428-019-0247-7

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Publishing type：Research paper (scientific journal)  

© 2020 American Chemical Society. The original synthetic strategy for a new type of poly(arylene vinylene) (PAV) is presented, where the C-C-bond-forming coupling of bis(alkoxycarbonyldiazomethyl)aromatic compounds is utilized as propagation. The strategy is unique in that the resulting PAVs have an alkoxycarbonyl group as an electron-withdrawing substituent on each vinylene carbon atom in the polymer main chain. Among the transition-metal catalysts examined in this study, RuCl(cod)Cp∗ (cod = 1,5-cyclooctadiene, Cp∗ = pentamethylcyclopentadienyl) is the most efficient, affording PAVs from a series of bis(alkoxycarbonyldiazomethyl)aromatic compounds with a high trans-C-C-forming selectivity of up to 90%. A PAV sample with a fluorenylene framework as an arylene moiety prepared by the Ru catalyst exhibited a hole mobility of 4 × 10-6 cm2 V-1 s-1.

DOI： 10.1021/acsomega.9b03408

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

© 2019 American Chemical Society. For polymerization of alkyl diazoacetates, the combination of a Pd complex bearing 1,4-naphthoquinone (NQ) or its derivatives as a ligand and borate, NaBPh4, was found to be an efficient initiating system. The polymerization of ethyl diazoacetate by a Pd(0) complex having two NQ molecules [Pd(nq)2] with NaBPh4 proceeded to give poly(ethoxycarbonylmethylene)s with a relatively high molecular weight (up to Mn = 36 kDa) in good yield (∼70%). This initiating system was also effective for polymerizing other diazoacetates, benzyl and cyclohexyl diazoacetates. In addition, in the presence of NaBPh4, a novel Pd(II) complex bearing an anionic naphthoquinonyl ligand derived from 2,3-dichloro-1,4-naphthoquinone (dichlone), [Pd(cod)(Cl-nq)Cl] (cod = 1,5-cyclooctadiene), which was newly prepared by treatment of a Pd(0) precursor, Pd2(dba)3·CHCl3 [dba = (E,E)-dibenzylideneacetone], with COD and dichlone, was capable of affording poly(alkoxycarbonylmethylene)s with much higher stereoregularity compared to the previously reported Pd-based initiating systems, despite a rather low polymer yield (∼20%). For both Pd(nq)-based initiating systems, Pd-Ph species generated by transmetalation with NaBPh4 were responsible for the initiation of diazoacetates based on MALDI-TOF-MS analyses of the resulting polymers, and naphthoquinones played unique important dual roles as both an oxidant and an anionic ligand for generating the active Pd(II) species.

DOI： 10.1021/acs.macromol.9b00857

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

Copyright © 2019 American Chemical Society. Rh-catalyzed three-component polycondensation of bis(diazoketone), bis(1,3-diketone), and tetrahydrofuran (THF) yielded poly(β-keto enol ether) via a simultaneous insertion of a diazo-bearing carbon atom of bis(diazoketone) with N2 elimination and a ring-opened THF into OH of an enol form of a 1,3-diketone moiety of bis(1,3-diketone). The β-keto enol ether linkage of the polymer can be efficiently cleaved under mild acidic conditions to afford a combination of two types of well-defined low molecular weight components in high yield. The degradation can indeed proceed even with trace of acid in CDCl3 solution in an NMR tube, while the polymer structure remained intact in a DMSO-d6 solution, demonstrating the high sensitivity of the β-keto enol ether linkage to acidic conditions. ©

DOI： 10.1021/acs.macromol.9b00653

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)  

© 2018 Elsevier Ltd Recent progress on polymerization of diazoacetates is described. Polymerization of diazoacetates has attracted much attention as an efficient method for C1 polymerization, which constructs C-C main chains from one carbon units. A variety of initiating systems consisting of Cu, Pd, B, and microwave activation have been revealed to afford polymers from diazoacetates with relatively low molecular weight. Rh-initiated polymerization of diazoacetates is remarkable for its ability of affording high molecular weight polymers in a stereospecific manner. The essence of the active species and mechanistic details for the Rh-initiated polymerization have been clarified by a combination of experimental and theoretical investigations. Copolymerization of diazoacetate with (CH2)n-affording monomers yielded unique polymer structures comparable to those of ethylene-acrylate copolymers. A series of postpolymerization modification approaches have been examined for the polymers obtained by the Rh-initiated polymerization. Some Pd-based initiating systems have been revealed to be effective for the polymerization of diazoacetates. A variety of substituents were introduced as ester substituents of diazoacetates, and they were polymerized by the Pd-based initiating systems. The effect of dense packing of the substituents on properties of the resulting polymers were examined in comparison to their vinyl polymer counterparts, and the enhanced properties in poly(substituted methylene)s were indeed observed in a number of examples.

DOI： 10.1016/j.polymer.2018.11.049

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

© 2018 Elsevier Ltd This study reported the control of molecular weights of functional polymer chains attached to the surfaces of the narrowly distributed environmentally responsive particles obtained from a single step process. As a proof-of-concept, a pH-responsive poly(L-glutamic acid) (PLGA) macromonomer with a degree of polymerization (n) of 50 or 260 was prepared by the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxy anhydride; this was performed using 4-vinylbenzylamine and was followed by hydrolysis. The pH-responsive PLGA macromonomer was further used as a stabilizer for the dispersion polymerization of styrene. Each macromonomer stabilized the dispersion polymerization, affording narrowly distributed polystyrene particles exhibiting pH-responsive aggregation or dispersion behavior, thereby indicating the graft of PLGA chains on the particle surface. Large particles with a low surface density were obtained using PLGA260. The particle sizes and surface glutamic acid densities were tunable over 0.8–2.0 μm and 0.4–1.8 unit/nm2, respectively, while maintaining narrow size distributions.

DOI： 10.1016/j.polymer.2018.10.040

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The excited-state dynamics of pyrene incorporated into poly(substituted methylene)s is investigated by picosecond time-resolved fluorescence spectroscopy and femtosecond time-resolved near-IR absorption spectroscopy in the 900-1400 nm region. The pyrene rings in poly (substituted methylene)s are photoexcited to the monomer excited state immediately after UV irradiation, followed by prompt excimer formation with time constants of a few picoseconds to a few hundred picoseconds. The excimer formation in poly(substituted methylene)s proceeds with much shorter time constants than that in pyrene-incorporated polyacrylates, vinyl polymer counterparts with the same side-chain structures, indicating the presence of stronger electronic interaction between the pyrene rings in poly(substituted methylene)s. The effects of every methylene substitution hold when each pyrene ring is connected to the polymer backbone with a monomethylene linker, while the effects are observed only weakly when a tetramethylene linker is employed. The results demonstrate the effectiveness of every methylene substitution in the prompt excimer formation of pyrene connected to the polymer backbone either directly or with the monomethylene linker.

DOI： 10.1021/acs.macromol.8b01060

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：John Wiley and Sons Ltd  

In this study, we estimated the chain nature of atactic and stereoregular poly(substituted methylene)s containing a phenylmethoxy side chain at each main-chain backbone carbon atom using synchrotron X-ray scattering to understand the topological and conformational properties of these rigid polymers. The atactic poly(substituted methylene) showed a linear chain nature. Contrastingly, the stereoregular poly(substituted methylene) exhibited a random coil structure. © 2018 Society of Chemical Industry.

DOI： 10.1002/pi.5532

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

© 2017 American Chemical Society. Pd-initiated polymerization of fluorine (F)-containing alkyl and phenyl diazoacetates is described. Polymerization of 2,2,2-trifluoroethyl diazoacetate [Et(CF3)DA] with π-allylPdCl afforded a C-C main chain polymer bearing a 2,2,2-trifluoroethoxycarbonyl group on each main chain carbon atom. The polymer showed upper critical solution temperature (UCST)-type phase separation in multiple common organic solvents with differing polarities. Although homopolymerization of 3,3,4,4,5,5,6,6,6-nonafluorohexyl diazoacetate [Hex(C4F9)DA] with a higher fluorine content yielded an insoluble product, copolymerization of Hex(C4F9)DA with non-fluorinated ethyl diazoacetate (EDA) proceeded homogeneously to give a soluble F-containing copolymer. Polymerization of a series of F-containing phenyl diazoacetates was also conducted with the same initiator, giving poly[(F-containing aryloxycarbonyl)methylene]s, which showed significant solubility differences depending on the substitution pattern of F atoms on the phenyl ring. Efficient postpolymerization modification of poly[(F-containing aryloxycarbonyl)methylene]s was achieved with a primary amine, affording a polymer with both a five-membered cyclic imide structure and an N-alkylcarbamoyl group in its side chains.

DOI： 10.1021/acs.macromol.7b01964

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society  

The cyclotriphosphazene-substituted diazoacetate homopolymer (polyPNDA′) (PNDA′ = hexaphenoxy-substituted phosphazene-containing methylene) and a novel poly(substituted methylene) block copolymer, polyPNDA′-block-poly(hexyloxycarbonylmethylene) (polyPNDA'-b-polyHDA′), were synthesized, and the self-assembly behavior of these polymers was studied in detail. A hexagonally packed aggregated structure was observed in the self-assembled structure of polyPNDA′, whereas a lamellar structure was observed in the microphase-separated nanoassembly of polyPNDA′-b-polyHDA′. These results indicate that a hierarchical structure composed of highly regular polyPNDA′ nanoaggregates and the long-range microphase-separated polyPNDA′ and polyHDA′ domains had formed.

DOI： 10.1021/acsmacrolett.7b00789

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Transition-metal-catalyzed N-H insertion of a diazocarbonyl compound is applied for polycondensation for the first time to give a new type of aromatic polyamine. The well-defined polyamines were obtained by [RuCl2(p-cymene)](2)-catalyzed reaction of diethyl1,4-phenylenebis(diazoacetate) with dianilines bearing a variety of linkers between two aniline units. The polycondensation proceeded at 30 degrees C in CH2Cl2 with 5.0 mol % of the Ru metal to [NH2 or N-2 = C] to afford the products with M-n = 6400-28 300 in moderate to high yield. Ethoxycarbonyl groups located at an adjacent position to NH imparted solubility to the polyamines, and their glass transition temperatures can be varied depending on the linker structure in a range of 88-173 degrees C.

DOI： 10.1021/acs.macromol.7b01994

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The initiating ability of a new system, amidinate/Pd, for the polymerization of diazoacetates is described. The system is effective in affording relatively high number-average molecular weight (M-n) polymers from ethyl diazoacetate (EDA, e.g., M-n = 45 100, 44% yield) and methyl diazoacetate (MDA, e.g., M-n = 26 200, 56% yield) in moderate yield. The polymerization of n-hexyl diazoacetate (nHDA) and benzyl diazoacetate (BDA) by the amidinate/Pd system yields high M-n polymers (M-n = ca.100 000), although the yield was below 10%. The system is also effective in the copolymerization of EDA with nHDA, BDA, and cyclohexyldiazoacetate (cHDA), affording high M-n copolymers in moderate yield. NMR spectra of the products obtained with the system suggest that the polymerization proceeds with significantly higher stereoregularity compared to that with previously reported Pd-based initiating systems.

DOI： 10.1039/c7py00816c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

A novel poly(L-lysine) macromonomer was successfully prepared via a click reaction between vinyl benzyl azide and propargyl-terminated poly(L-lysine), and it was used as a functional stabilizer for the dispersion polymerization of styrene; narrowly distributed polystyrene particles were produced as a result, onto which cationic poly(L-lysine) chains were grafted. The resulting particles exhibited a pH responsive dispersion behavior in aqueous solutions due to the properties of the poly(L-lysine) chains at the particle surface. It was found that the particle size and the surface density of the resultant particles could be varied by tuning the concentrations of the macromonomer, styrene, and initiator used in the initial solution of the dispersion polymerization. The poly(L-lysine) macromonomer was also found to be effective when used as a stabilizer for the dispersion polymerization of both methyl methacrylate and a styrene/acrylonitrile mixture. (C) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2017.04.077

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Cyclopolymerization of bis(diazocarbonyl) compounds is described for the first time. By choosing appropriate reaction conditions and monomer structures, the cyclopolymerization of bis(diazoacetate)s efficiently proceeded to give carbon-carbon main chain cyclopolymers with well-defined structures, as confirmed by MALDI-TOF-MS analyses. The products are a new kind of cyclopolymer with respect to polymer structure: there exists no free methylene in the sp(3)-carbon-based polymer backbone in contrast to conventional cyclopolymers prepared from divinyl compounds, which inevitably have free methylenes in and between cyclic units in their polymer backbones. The resulting cyclopolymers with closely aligned cyclic units along the polymer backbone showed a much higher glass transition temperature compared to the corresponding polymers without cyclized repeating units.

DOI： 10.1021/acs.macromol.6b01809

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Recent developments of Pd-initiated polymerization of diazoacetates are described. Polymerization of diazoacetates is a useful method for preparing C-C main chain polymers bearing an ester substituent on each main chain carbon atom [poly(substitutcd methylene)s]. However, the substituents introduced into the side chain were limited to hydrophobic groups, and controlled polymerization has not been achieved so far. Recently, we have successfully synthesized poly(substituted methylene^ with hydrophilic groups including hydroxy group and oligo(ethylene glycol) units. The resulting polymers were found to show higher hydrophilicity compared to the corresponding vinyl polymer counterparts. In addition, we have succeeded in controlling the polymerization of diazoacetates for the first time by employing cyclophosphazene-containing diazoacetates as monomers.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

A new carbon-carbon main chain polymer with N-phenyl-2,6-dimethoxybenzamide on its each main chain carbon atom is prepared by Pd-initiated polymerization of diazoacetate containing the benzamide group, and the Li ion conductivity of the polymer doped with lithium bis(trifluoromethylsulfonyl)imide is evaluated along with its vinyl polymer counterparts with the same benzamide substituent. Although the expected high ion conductivity at low temperatures derived from a unique ion transport mechanism based on the bond rotation in the benzamide moiety reported in a literature is not observed, it is revealed that the dense packing of the benzamide group along the polymer main chain results in the enhanced ion conductivity. In addition, investigation of the correlation between ion conductivity and glass transition temperature of these solid polymer electrolytes (SPEs) reveals that other ion transport mechanism would operate in the benzamide containing SPEs than that derived from segmental motion of polymer chains observed in PEO-based SPEs. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ssi.2016.05.001

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Pd-initiated polymerization and oligomerization of diazo compounds containing a dialkoxyphosphinyl group are described. Polymerization of 2-dialkoxyphosphinylethyl diazoacetates with pi-allylPdCl-based initiating systems afforded C-C main chain polymers bearing phosphonate on each main chain carbon atom. The quantitative transformation of the side chain phosphonate to phosphonic acid resulted in the formation of water soluble polymers having the acid groups accumulated around their main chains, although the carbonyl ester linkage in the side chain was cleaved via intramolecular acid-assisted hydrolysis in water at 80 degrees C. Pd-initiated oligomerization of diethyl diazomethylphosphonate yielded an oligomeric product bearing diethoxyphosphiny groups directly attached to its main chain carbons, with unexpected incorporation of azo group in the main chain framework. Hydrolysis of the phosphonate of the oligomer afforded a water-soluble product, which was revealed to show higher proton conductivity than poly(vinylphosphonic acid) under certain conditions. (C) 2016 Wiley Periodicals, Inc.

DOI： 10.1002/pola.28030

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

A novel macromonomer composed of poly(a-L-glutamic acid) was used as a stabilizer for dispersion polymerization of styrene in DMF-water medium with AIBN initiator, giving narrowly-distributed functional polystyrene particles on which the poly(a-L-glutamic acid) was grafted. The resultant particles had 0.54-2.12 mm in size and 0.2-2.6 residue/nm(2) in surface density and showed a pH-responsive colloidal behavior associated with a helix-coil transformation of the surface poly(a-L-glutamic acid). Not only the particle size but also the surface density were controlled with macromonomer concentration, macromonomer length, DMF composition, and styrene concentration, while no consistent trend for AIBN concentration was observed. A gel-permeation-chromatography curve of the particles was separated into three components. We tentatively identify the origin of each component and propose a possibility that unstable particles, which were generated even after the growing particles were stabilized, took an important role in particle growth and size distribution of the resultant particles. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2015.06.022

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WILEY-V C H VERLAG GMBH  

Pd-initiated polymerization of alkyl diazoacetates as an effective methodology to prepare carbon-carbon (CC) main chain polymers bearing a substituent on every main chain carbon is described. (NHC)Pd/borate (NHC=N-heterocyclic carbene) systems are efficient at affording high M-n polymers. pi-AllylPdCl-based systems can initiate the polymerization with the number of polymer chain per Pd ratios over 1.0 because of occurrence of chain transfer, capable of affording relatively low M-n polymers in high yield. Initiation and termination mechanisms have been proposed for the latter initiating systems, based on the detailed MALDI-TOF-MS analyses of the low M-n products.

DOI： 10.1002/masy.201400007

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Polymerization of cyclophosphazene-containing diazoacetates was carried out using a (eta(3)-C3H5) PdCl-based initiating system to produce sp(3)-sp(3) carbon-carbon main chain polymers bearing a cyclophosphazene-containing ester group on every main chain carbon atom. The obtained polymers had very narrow molecular weight distributions in contrast to the case of other alkyl or aryl diazoacetates reported previously, suggesting that the polymerization of cyclophosphazene-containing diazoacetates proceeded in a controlled manner without apparent side reactions, which was confirmed by MALDI-TOF-MS analysis. In addition, block copolymers with a well-defined structure were successfully synthesized. This is the first report on controlled polymerization of diazoacetates to afford narrow molecular weight distribution polymers. Furthermore, thermogravimetric analysis was conducted to reveal that the resulting polymers had a higher thermal stability compared to the vinyl polymer counterparts.

DOI： 10.1039/c5py00532a

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

We describe the polymerization of a variety of diazocarbonyl compounds initiated with Pd complexes. Relatively low molecular weight polymers (M-n = ca. 2000) were obtained by the polymerization of diazoacetates, diazoketones, and diazoacetamides initiated with PdCl2. On the other hand, the polymerization of diazoacetates by (NHC)Pd/borate and pi-allyl-PdCl-based systems can afford high molecular weight polymers (M-n &gt; 10000). Chain-end structure analyses by using MALDI-TOF-MS was used to elucidate initiation and termination mechanisms for the pi-allyl-PdCl-based systems. Polymerization of hydroxy-containing diazoacetates resulted in the formation of unique polymers with densely accumulated hydroxy groups around their C-C main chains.

DOI： 10.1295/koron.2014-0100

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Synthesis and characterization of polymers with densely-grafted oligo(ethylene glycol)s (OEGs) are described. Polymerization of OEG-containing diazoacetates with (eta(3)-C3H5)PdCl-based initiating systems afforded C-C main chain polymers bearing OEGs on each main chain carbon atom. The polymers with a short OEG side chain showed a lower critical solution temperature-type phase separation in an aqueous medium; the transition temperatures were higher than those of the corresponding vinyl polymers with the same oxyethylene chain length. In addition, the Li-ion conductivity was examined to reveal that the polymers with densely-grafted OEGs showed higher values than the corresponding vinyl polymers, despite the fact that no significant difference in the glass transition temperature was observed between the two types of polymers.

DOI： 10.1039/c5py01378j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

A block copolymer composed of polystyrene and poly(alpha-L-lysine hydrobromide) (PLL) segments was used as a stabilizer for dispersion polymerization of styrene in water-methanol medium to give narrowly-distributed polystyrene particles in the size range from 0.36 to 1.09 mu m, on which the PLL segment was grafted with a surface density of 0.2-3.4 L-lysine residue/nm(2). We investigated effects of polymerization time, stabilizer concentration, segmental composition of the block copolymer, and composition of the medium on surface structure and particle size of the affording particles. Interestingly, we obtained an experimental evidence that the surface density of the PLL clearly depends on structural parameters of the stabilizer and various polymerization conditions. Based on the dependence, it was possible to control the surface density of the narrowly-distributed particles within the range between the minimum and the maximum density limits of the graft chain by changing the structure of the stabilizer and polymerization conditions. Conformation of the PLL, which underwent a helix-coil transformation with an increase in water composition of the medium, had a strong effect on the surface structure, the size, and property of the resulting particles. Further modification of the particle surface was possible by utilizing the amino groups in the PLL graft. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2014.06.069

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Two types of polymerization of hydroxy-containing diazoacetates are described. The polymerization of hydroxy-containing diazoacetates using palladium complexes proceeded successfully under chain-growth mechanism even without a protecting group to give C-C main chain polymers bearing a hydroxy-containing ester substituent on each carbon of the backbone. The resulting polymers had a slightly branched structure due to chain transfer reaction with the hydroxy groups, while the polymers obtained by polymerization of silyl-protected diazoacetates and subsequent deprotection had a completely linear structure. The hydroxy-containing polymers with an appropriate hydrophilic/hydrophobic balance showed a lower critical solution temperature-type phase separation in an aqueous medium. On the other hand, the polymerization of hydroxy-containing diazoacetates using InCl3 as a catalyst proceeded under step-growth mechanism to give oligomers having a distinct repeating unit (ester-ether), where a new ether bond was generated through O-H insertion reaction of diazocarbonyl groups into hydroxy groups.

DOI： 10.1021/ma500783b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A variety of aliphatic- and aromatic-type unsaturated polyesters (UPs) were prepared by transition-metal-catalyzed single-component polycondensation of bis(diazoacetate)s under a mild condition. With the second-generation Grubbs catalyst, the polycondensation proceeded exclusively through an intermolecular highly cis-selective C=C forming coupling of diazo-bearing carbons with N-2 release, giving well-defined UPs. The cis-C=Cs of the resulting polymers could be isomerized quantitatively into trans-C=Cs with a catalytic amount of diethylamine. Additionally, other metal complexes, the first-generation Grubbs catalyst, rhodium(II) acetate, and copper(II) acetylacetonate, also produced UPs from the bis(diazoacetate)s, with lower stereoselectivities, although an unexpected carbene oligomerization of the monomers partially occurred along with the C=C bond-forming coupling.

DOI： 10.1021/ma401047x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

The radical copolymerization of alkyl 2-norbornene-2-carboxylates, 1a-c, with alkyl (meth)acrylates, to produce copolymers with norbornane in the main chain, is described here. gamma-Butyrolactone-and hydroxy group-containing norbornene-based monomers (1b and 1c, respectively) were freshly synthesized, and their radical copolymerization behavior with n-butyl acrylate was examined. Methyl 2-norbornene-2-carboxylate, 1a, and the new monomers, 1b and 1c, were employed as comonomers for radical terpolymerization with lactone-and adamantane-containing (meth) acrylates to produce copolymers that could be applied as new, more chemically robust 193-nm photoresist materials. The dissolution rate of the spin-coated copolymer films after exposure to a photoacid generator, a significant characteristic in the photoresist application, was measured for various exposure doses of 193-nm ArF laser light under standard conditions in an aqueous alkaline solution.

DOI： 10.1038/pj.2012.180

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Radical copolymerization behavior of alkyl cyclobutenecarboxylate-derivatives 4-6 and related norbornene-derived compounds 79 is described. A variety of alkyl cyclobutenecarboxylates fused with cycloaliphatic framework (46) were prepared by [2 + 2] cycloaddition of five, six, and eight-membered cycloolefins with alkyl propiolates [alkyl = Me, 2-hydroxyethyl, and 3--butyrolactonyl (-BL)]. The fused cyclobutenecarboxylates 46 were radically copolymerized with n-butyl acrylate (nBA) to afford random copolymers, and terpolymerized with alkyl methacrylates with bulky ester groups [alkyl = -BL and 3-(3-methyladamantyl)]. The cyclobutane-containing bicyclic framework incorporated in the resulting polymer backbone contributes to raising Tg of resulting copolymers. Similar results were obtained when a mixture of related norbornene-derived compounds were used as monomers with an apparently enhanced Tg-raising effect in the copolymerization with nBA. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 27162724

DOI： 10.1002/pola.26668

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Pd-mediated polymerization of 1-pyrenylmethyl diazoacetates affords poly(1-pyrenylmethoxycarbonylmethylene) (poly4′), whose CC main chain is tightly surrounded by pyrene groups. The intensity ratio of excimer emission to monomer emission (I E /I M ) of poly4′ was more than 20 times higher than that of its vinyl polymer counterpart of poly(1-pyrenylmethyl methacrylate) (polyPyrMA), clearly demonstrating much higher efficiency for excimer formation in poly4′, because of the tight arrangement of the pyrene groups around the main chain. Copyright © 2012 Wiley Periodicals, Inc.

DOI： 10.1002/pola.26480

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

A block copolymer (PS-b-poly(L-Glu)) composed of polystyrene and poly(L-glutamic acid) was used as a stabilizer for dispersion polymerization of styrene. When dispersion polymerization of styrene was conducted at 70 degrees C in 80% dimethylformamide-water with 0.5 wt% PS-b-poly(L-Glu), spherical polystyrene particles with D-n = 0.72 mu m and narrow size distribution were obtained. Whereas AIBN concentration did not have any effects on particle size, molecular weight of the polystyrene particles was strongly dependent on the initiator concentration. As concentration of the PS-b-poly(L-Glu) increased from 0.2 to 1.0 wt%, particle size decreased from D-n = 0.91 to 0.69 mu m with keeping surface area occupied by one poly(L-glutamic acid) chain about S = 50 nm(2). On the other hand, an increase in initial concentration of styrene from 2 to 20 wt% caused an increase in particle size from D-n = 0.48 to 1.36 mu m and a decrease in surface area per poly(L-glutamic acid) block from S = 91 to 45 nm(2). Colloidal stability of the polystyrene particles in aqueous solution was responsive to pH due to the surface-grafted poly(L-glutamic acid). For dispersion polymerization of styrene, the PS-b-poly(L-Glu) functions as both a stabilizer and a surface modifier. (C) 2012 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcis.2012.08.040

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Polymerization of ethyl and benzyl diazoacetates (EDA and BDA) initiated with pi-allylPdCl-based systems [pi-allylPdCl/NaBPh4, pi-allylPdCl/NaBAr4F (Ar-F = 3,5-{CF3}(2)C6H3), and pi-allylPdCl] is described. Initiation efficiencies of the pi-allylPdCl-based systems are much higher than those of the previously reported (NHC)Pd/borate (NHC = N-heterocydic carbene) systems, and the new systems are capable of polymerizing the alkyl diazoacetates at low temperatures (0 similar to -20 degrees C), where the (NHC)Pd/borate systems cannot initiate the polymerization. MALDI-TOF-MS analyses of the polymers obtained from EDA provide information for the chain-end structures of the polymers, based on which initiation and termination mechanisms are proposed. Interestingly, EDA polymerization by the pi-allylPdCl-based systems in the presence of alcohols (EtOH, nPrOH, and nBuOH) or water was found to afford RO- or HO-initiated polymers as major products, as confirmed by MALDI-TOF-MS analyses.

DOI： 10.1021/ma3013527

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

The helix-coil transformations of block copolymers composed of poly(gamma-benzyl-L-glutamate) (PBLG) and polystyrene (PS), in which PS was attached to either the N terminus (PBLG(n)-N-PSm) or the C terminus (PSn-C-PBLG(m)) of PBLG, were investigated in trifluoroacetic acid (TFA)-chloroform mixtures with TFA concentrations in the range of 0.7-10 vol%. The helical content (f(H)) estimated from H-1 nuclear magnetic resonance measurements indicated that the PBLG segment in PBLG(55)-N-PS160 underwent a gradual helix-coil transformation from f(H) = 1 to f(H) = 0.75 over the range of 3.6-5.7 vol% TFA and then a drastic transformation to f(H) = 0 at 9.5 vol% TFA, in a manner similar to that of the PBLG(55) homopolymer. In PS120-C-PBLG(55), the helical deformation of the PBLG segment was observed by adding a very small amount of TFA (0.7-3.6 vol%), followed by gradual and drastic transformations at higher TFA concentrations. The results indicate that the conformational stability of the C terminus in a PBLG chain differs from that of the N terminus. Transformations of PBLG/PS block copolymers with various molecular weights and compositions were also studied. Polymer Journal (2012) 44, 189-194; doi:10.1038/pj.2011.113; published online 26 October 2011

DOI： 10.1038/pj.2011.113

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

New types of poly(ester ether ketone)s 3 and 8 were prepared by three-component polycondensation of bis(diazoketone) 1 with a variety of dicarboxylic acids 2 and THF or THP catalyzed by Rh(2)(OAc)(4). THF was ring-opened and incorporated into almost every carboxyl O-H of 2 via simultaneous insertion together with a diazocarbonyl-derived carbene, resulting in the formation of a unique poly(ester ether ketone) framework. On the other hand, when THP was used as a cyclic ether, insertion of carbene alone into the carboxyl O-H (normal insertion) competes with the simultaneous insertion of THP and carbene, and the ratio of the two modes of insertion depends on the kind of 2 employed. The mode and selectivity of the propagation were confirmed by conducting Rh-catalyzed model reactions of diazoacetophenone 4 with 4-tert-butylbenzoic acid 5 in THF and THP.

DOI： 10.1021/ma201037p

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

(NHC)Pd/borate initiating systems (NHC = N-heterocyclic carbene) were applied for polymerization of alkyl diazoacetates with a variety of ester groups. The monomers with n-hexyl, cyclohexyl, benzyl, and cholesteryl group as an ester group were transformed into the corresponding poly(alkoxycarbonylmethylene)s with M-n &gt; 10 000. On the other hand, the polymerization of 1-adamantyl diazoacetate afforded low-M-n polymers (M-n &lt; 4000), probably because of steric reasons. Copolymerization of a few comonomer combinations also proceeded successfully to give copolymers with M-n &gt; 20 000.

DOI： 10.1021/ma200064b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Thermally induced polymerization of diazoketones, (E)-1-diazo-3-nonen-2-one 1 and (E)-1-diazo-4-phenyl-3-buten-2-one 2, is described. Heating 1 and 2 in a solvent at 60-100 degrees C afforded polymers, where all the main chain carbons bear acyl groups derived from the monomers and the main chain contains ca. 25-35 mol% of azo group. Molecular weight of the resulting polymers increased up to M(n) = 8,400 by the addition of benzoquinone to the reaction mixtures. The polymerization was supposed to proceed via radical propagating chain end and copolymerization of 1 with styrene gave copolymers (M(n) = 11,000-15,000) having acylmethylene, azo group, and repeating unit from styrene in their main chains.

DOI： 10.1007/s00289-010-0254-5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Radical copolymerization of di(isobutoxy)methylvinylsilane 1 and di(isobutoxy)phenylvinylsilane 2 with methyl methacrylate (MMA) and n-butyl acrylate (n-BA) was carried out, and the oxidative cleavage of Si-C bonds in the resulting copolymers was examined to prepare copolymers having repeating units of vinyl alcohol (VA). Although the incorporation of 1 and 2 in the copolymerization of these alkoxyvinylsilanes with MMA was not so effective (1 or 2 content &lt; 18 mol%), MCPBA-induced oxidative transformation of a poly(2-co-MMA) with 9.0 mol% of 2 content proceeded efficiently, giving a poly[(vinyl alcohol)-co-MMA]. On the other hand, whereas poly(1 or 2-co-n-BA)s with relatively higher 1 or 2 contents (up to 45 mol%) can be prepared by the radical copolymerization of 1 or 2 with n-BA, oxidation of the copolymers afforded insoluble products.

DOI： 10.1007/s00289-009-0190-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A series of new polyetherketones was prepared by Rh-catalyzed polycondensation of bis(diazocarbonyl) compounds 1a-c with aromatic diols 2A-C in cyclic ethers (THF, THP, and 1,4-dioxane). In addition to the expected insertion of diazo-bearing carbon of I a c into O-H of 2A-C releasing N(2), unexpected incorporation of the ring-opened cyclic ethers between the diazo-bearing carbon of I a c and phenolic oxygen of 2A-C occurred, providing the polymer main chains with additional oxyalkylene units. The extent of-cyclic ether incorporation relative to the expected insertion depended on the kind of the cyclic ether: THF, 95-98%; THP, 26-32%; 1,4-dioxane, 11-21%. Polyetherketones with a variety of main chain structures can be prepared by the new polycondensation.

DOI： 10.1021/ma100494a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Radical copolymerization behavior of methyl 2-norbornene-2-carboxylate 1 and 2-phenyl-2-norbornene 2 was investigated. Radical copolymerization of 1 and 2 with styrene, alkyl acrylate, and methyl methacrylate in a variety of monomer combinations afforded copolymers, whose main chains consisted of norbornane framework. Relative monomer reactivity ratios for the copolymerization of 1 and 2 with n-butyl acrylate (n-BA) were determined by the Fineman-Ross method. Temperature-modulated DSC analysis for poly(l or 2-co-n-BA)s revealed remarkable T(g)-raising effect of incorporation of norbornane framework into the polymer main chain, compared to that effect of styrene repeating unit. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2009.12.008

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Language：English   Publishing type：Part of collection (book)   Publisher：SPRINGER-VERLAG BERLIN  

This review describes recent progress in the preparation of C-C main chain polymers, where the main chain is constructed from one carbon unit. The first example for this strategy is polymerization of diazoalkanes and aryldiazomethanes, which were extensively explored in the period 1950-1970, despite the high explosiveness of the monomers. The metal surface-catalyzed polymerization of diazoalkanes has recently attracted much attention, as an efficient method for coating the surface with nanometer-scale polymethylene thin films, which can be regarded as a useful substitute for polyethylene films. Diazocarbonyl compounds such as diazoacetates, diazoketones, and diazoacetamides with a variety of substituents have been polymerized by Pd-complexes to give poly(substituted methylene)s with polar functional groups. Rh(diene) complexes polymerize ethyl diazoacetate in a stereospecific mariner, giving high molecular weight polymers (M-n up to 270,000). Organoborane-initiated living polymerization of sulfoxonium methylides is remarkably effective as a method for preparing polymethylenes with a controlled chain length and a well-defined polymer architecture. Some polymerizations related to the above examples are also described.

DOI： 10.1007/12_2009_46

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Language：Japanese   Publisher：公益社団法人 日本化学会  

DOI： 10.20665/kakyoshi.58.11_520

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The Pd(O) complexes with N-heterocyclic carbene (NHC) ligand [(NHC)Pd] in conjunction with tetraarylborate [(NHC)Pd borate systems] which are capable of transforming ethyldiazoacetate (EDA) into poly(ethoxycarbonylmethylene)s M n &gt; 20000 has been reported. The crude product obtained after the removal of volatiles from the reaction mixture was purified by using preparative recycling GPC to give a colorless solid. The complexity of the MS charts indicates the non-uniformity of the (NHC) Pd borate system with respect to the initiation and termination, thus, leading to the aforementioned low controllability of the polymerization with respect to the molecular weight of products. The generality of the polymerization of diazocarbonyl compounds as a practical method for polymer synthesis is also reported.

DOI： 10.1021/ma901857s

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

The effects of polystyrene-b-poly(aminomethyl styrene) (PSn-b-PAMS(n)) stabilizers on the particle size (D-n) and size distribution (PSD) in dispersion polymerization of styrene were investigated. The block copolymers, PSn-b-PAMS(m), were prepared as follows: (i) atom transfer radical polymerization (ATRP) of styrene (PS-Br), (ii) ATRP of vinylbenzylphthalimide with the PS-Br (PS-b-PVBP), and (ill) treatment of the PS-b-PVBP with hydrazine. When the dispersion polymerization of styrene proceeded at 60 degrees C in ethanol with PS19-b-PAMS(130) stabilizer, spherical polystyrene particles with D-n = 0.91 mu m (PSD = 1.01) were obtained. The particle size was strongly affected by the copolymer composition. With an increase in PAMS block length from m = 54 to 100 in PS17-b-PAMS(m), particle diameter became smaller from 1.55 to 0.91 pm. On the other hand, an increase in the length from m = 20 to 82 in PS34-b-PAMS(mS) caused an increase in particle size from 0.35 to 0.70 mu m. Titration of the particles suggests that 14-81% of stabilizers used in the polymerization system were attached on the polystyrene particle Surfaces, depending on the composition of the block copolymers. Thus, for the dispersion polymerization Of Styrene, PSn-b-PAMS(m) block copolymers have both functions as a stabilizer during polymerization and surface-modification sites Of polystyrene particles. (c) 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcis.2008.10.052

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

Pd-mediated copolymerization of bifunctional diazocarbonyl compounds, 1,1&apos;-bis(diazoacetyl)ferrocene 2, 4.4&apos;-bis(diazoacetyl)biphenyl 5, and bis(4-diazoacetylplienyl)dimethylsilane 6, with monofunctional diazoketones, (E)-1-diazo-3-nonen-2one 3 and (E)-1-diazo-4-phenyl-3-buten-2-one 4, and ethyl diazoacetate 7 was examined in order to prepare a new type of crosslinked polymer. Although copolymerization of 2 with 3 and 4 proceeded in the presence Of PcCl(2)(MeCN)(2), the products were soluble in CHCl(3) and their M(n)s were rather low irrespective of the feed ratio of the comonomers, probably because Of the occurrence of intramolecular cyclization of two diazoacetyl groups in 2. On the other hand, copolymerization of 5 and 6 with 3, 4, and 7 with relatively high feed ratios of the bifunctional monomers afforded products insoluble in CHCl(3), which suggested the formation of crosslinked polymers. In addition, Pd-mediated (co)polymerization of monofunctional diazoacetylferrocene 1, monofunctional counterpart to 2, was examined, resulting in the formation of a new type of ferrocene-containing polymer.

DOI： 10.1295/polymj.PJ2009065R

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Copolycondensation of alpha,alpha-dibromotoluene (1) with alpha,alpha'-dibromo-p-xylylene (2) was found to proceed in the presence of excess Mg via nucleophilic substitution of in situ generated Grignard reagents to Br-bearing benzylic carbons. The use of dichlorodimethylsilane (3) and 1,6-dibromohexane (4) as a comonomer in the ternary copolycondensation with 1 and 2 was effective to give higher molecular weight polymers by improving their solubility. In the series of the copolycondensation, the copolymer with the highest M-n of 8480 was obtained in a 41% yield by the reaction of a feed ratio of [1]:[2]:[4] = 1:1:1 in THF at room temperature.

DOI： 10.1007/s00289-007-0858-6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Palladium-mediated polymerization of cyclic diazoketones was investigated. Although cyclic diazoketones 1a,b derived from cyclohexanone and 1-tetralone did not homopolymerize, they can be used as a comonomer for copolymerization with polymerizable acyclic diazoketones. On the other hand, an alpha,beta-unsaturated cyclic diazoketone 2a prepared from 2-cyclohexen-1-one polymerized to give a polymer poly2a' with M-n = 1400 in a 23.8% yield. Addition of some nucleophiles to C=C bond in poly2a' was carried out. Copolymerization of 2a and its dimethyl-substituted analogues 2b,c with acyclic diazoketones was also investigated. (C) 2008 Wiley Periodicals, Inc.

DOI： 10.1002/pola.22504

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

Palladium-mediated polymerization of diazoacetamides bearing various substituents 1-4 is described. Homopolymerization of monomers with n-hexyl or 4-n-octylphenyl group on the nitrogen afforded polymers [poly(N-substituted carbamoylmethylene)], whose all the main chain carbons have N-substituted carbamoly groups. Elemental analysis of the products indicated incorporation of azo group in the main chain. Copolymerization of diazoacetamides 1-4 with a diazoketone. (E)-1-diazo-4-phenyl-3-buten-2-one 5, proceeded efficiently, giving poly(substituted methylene)s with a variety of N-substituted carbamoyl groups in their side chains.

DOI： 10.1295/polymj.PJ2008145

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DOI： 10.5059/yukigoseikyokaishi.66.358

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Radical (co)polymerization behavior of alkoxyvinylsdanes [tri(isobutoxy)vinylsilane 1, triethoxyvinylsilane 2, di(isobutoxy)-methylvinyisilane 3, di(isobutoxy)phenylvinyl si lane 4, diethoxymethylvinylsilane 5, and diethoxyphenylvinylsilane 6] was systematically investigated. Homopolymerization and copolymerization with styrene of these alkoxyvinylsilanes were performed under various conditions in order to find appropriate initiating systems for the radical polymerizations. Transformation of some of the copolymers into poly[(vinyl alcohol)-co-styrene]s was examined via oxidative cleavage of the Si-C bonds in the alkoxyvinylsilane repeating units.

DOI： 10.1295/polymj.PJ2008113

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Polymerization of diazoketones mediated by organoaluminum compounds was investigated. Trialkylaluminum R3Al (R = iBu, Et, Me) and diisobutylaluminum hydride (DIBAL) polymerized (E)-1-diazo-3-nonen-2-one (1) to give polymers with M. = 2000-3500, which contained nearly 33 mol % of azo group (-N=N-) along with the dominant acylmethylene unit in the main chain. On the other hand, when (E)-1-diazo4-phenyl-3-buten-2-one (2) was used as a monomer for the organoaluminum-mediated polymerization, the resulting polymers had ethylidene (-CH[CH3]-) units in the main chain along with acylmethylene and azo group, as a result of reductive cleavage of the acyl group during the polymerization. (c) 2007 Wiley Periodicals, Inc.

DOI： 10.1002/pola.22266

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Radical copolymerization of alkyl 2-norbornene-2-carboxylates (alkyl = Me 1a, nBu 1b) with alkyl acrylates (alkyl = ethyl, methyl, and n-butyl) was investigated. Copolymerization of 1a,b with the alkyl acrylates initiated by 1,1'-azobis (cyclohexane-l-carbonitrile) at 85 degrees C proceeded to give random copolymers, although the homopolymerization of 1a,b did not proceed efficiently under the same conditions. Typically, bulk copolymerization of la with ethyl acrylate in a feed ratio of 1:3 ([1a]:[EA]) afforded a copolymer with Mn = 33,300 containing 19.4 mol % of 1a unit in the composition. An increase of T-g derived from the incorporation of the rigid norbornane framework was observed, although the extent of the temperature rise was rather moderate. The ternary radical copolymerization of 1a,b/alkyl acrylate/N-phenylmaleimide proceeded to give copolymers with the three repeating units in the main chain. (c) 2007 Wiley Periodicals, Inc.

DOI： 10.1002/pola.22197

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

As a novel synthetic strategy for copolymers of vinyl alcohol, we propose herein copolymerization of alkoxyvinylsilanes with other vinyl monomers, followed by oxidative cleavage of the alkoxysilyl groups attached to the main chain of the resulting copolymers. Radical copolymerization of di(isobutoxy)methylvinylsilane 1 with styrene afforded poly(1-ran-styrene)s with a variety of compositions of both repeating units, although the M-n's (&lt;9000) and yields (&lt;35%) were rather low. The oxidative cleavage of the alkoxysilyl groups in the copolymers with m-chloroperbenzoic acid proceeded efficiently, giving poly(vinyl alcohol-ran-styrene)s, which were soluble in common organic solvents. The structures of the poly(vinyl alcohol-ran-styrene)s were characterized by NMR, GPC, elemental analysis, and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS). (C) 2007 Wiley Periodicals, Inc.

DOI： 10.1002/pola.22114

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The role of cyclophosphazenes with oxyethylene chains (N3P3(OCH2CH2)(n)OCH3, (n = 3, 3, n = 7.2, 4) and N4P4[OC6H4O(CH2CH2O)(7.2)CH3](8) (8) for the synthesis and ionic conductivity in polymethacrylate networks was studied. Reflecting the structural features of cyclophosphazenes, the Li-7 NMR spectra of the mixture of 3 and LiN(SO2CF3)(2) showed that more than 40% of the Li+ salt could exist as a free ion at room temperature. Similar values were obtained for 4 and 8. Cross-linked methacrylate polymers (12-14, and 16-18) were prepared from the reaction of poly(ethylene glycol) methyl ether methacrylate and poly(ethylene glycol) dimethacrylate both in the presence of these cyclophosphazenes which act as molecular imprinting molecules (method II, M-II) and without the cyclophosphazene (method I) DSC studies of the imprinted polymer, 12(20)/3/Li+ system after removal of the cyclophosphazene showed that the glass transition temperature range (Delta T-g) becomes significantly narrower compared to that of the unimprinted 11(20)/3/Li+ system, where cross-linked polymer 11(20) was prepared in the absence of the cyclophosphazenes (method I, M-I). The ionic conductivity of the Li+/cross-linked polymer system was improved by the subsequent readdition of the cyclophosphazenes. The 12(20)/3/Li+ complex showed a conductivity of 1.1 x 10(-3) S/cm at 90 degrees C, which was two times higher than that of the 11(20)/3/Li+ complex. The effectiveness of the small molecule imprinting technique for the preparation of cross-linked polyelectrolytes with high conductivity and mechanical stability is discussed.

DOI： 10.1007/s10904-007-9126-3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Phenyldiazomethane was found to be polymerized by the reaction with palladium-based initiating systems. Homopolymerization of phenyldiazomethane afforded a polymer, whose main chain consists of phenylmethylene framework (-CHPh-) and azo groups (-N=N-). The incorporation of the azo group was suggested from the results of elemental analyses, and confirmed by Raman spectroscopy. Palladium-mediated copolymerization of phenyldiazomethane with (E)-1-diazo-3-nonen-2-one or ethyl diazoacetate proceeded to give copolymers having phenylmethylene framework, azo group, and acylmethylene or ethoxycarbonylmethylene framework in the main chain, with a variety of their compositions. (c) 2006 Wiley Periodicals, Inc.

DOI： 10.1002/pola.21881

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The anionic polymerization of methyl methacrylate (MMA) was initiated with a mixture of lithium amide of various secondary amines and nBuLi in the presence of YCl3, where an Y-ate complex was formed and an amide ligand on Y attacked MMA nucleophilically. In THF at -78 degrees C, PMMAs with narrow molecular weight distributions were obtained in high yields. The presence of a secondary amino group derived from the initiator at the polymer chain end was confirmed by MALDI-TOF-MS analyses. The initiating system using indoline as a secondary amine was effective for block copolymerization of MMA with tert-butyl acrylate (tBA), giving poly(MMA-b-tBA)s with narrow molecular weight distributions. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jorganchem.2006.08.039

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Publisher：The Society of Polymer Science, Japan  

DOI： 10.1295/kobunshi.56.34

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Temperature dependences of conformations of poly(beta-phenethyl-L-aspartate) (PA) in block copolymer systems, in which polystyrene (PS) was attached to either N-terminus (PA(n)-N-PSm) or C-terminus (PSn-C-PA(m)) of the PA, respectively, were investigated in 1,1,2,2-tetrachloroethane (TCE) solutions by using H-1 NMR spectroscopy. The block copolymers were synthesized by combination of atom transfer radical polymerization and ring-opening polymerization of N-carboxy amino acid anhydride. Whereas PA homopolymer (H-PA(n), n = 68) with right-handed helical conformation started to transform to left-handed structure at 70 degrees C, the helical-sense inversion of PA(68)-N-PS38 occurred at a lower temperature, 40 degrees C. Further transformation from left-handed conformation was not observed for both polymers in the temperature range of 70 degrees C to 110 degrees C. On the other hand, H-1 NMR spectra of PS70-C-PA(170) showed coexistence of right- and left-handed helices of PA at 8.2 and 8.8 ppm at 30 degrees C, respectively. These peaks, however, disappeared above 90 degrees C, and a new peak at 8.5ppm was observed. Thus, the introduction of PS chain into PA termini affected conformational stability of PA in a different way, although the transformational behaviors were not influenced by the difference of the chain length of PS segments.

DOI： 10.1295/polymj.PJ2007020

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

alpha,alpha-Dibromotoluene 1 was found to be polymerized by the reaction with excess Mg to give poly(phenylmethylene)s 2, whose main chains were partially dehydrogenated to carbon-carbon double bonds (C=C). The C=Cs in 2 can be brominated by treatment with Br-2. The polymerization mechanism was presumed to include the formation of Grignard reagents of various species with benzylic C-Br bonds and the nucleophilic attacks of the Grignard reagents to various compounds with benzylic C-Br bonds. Copolymerization of 1 with dichlorodimethylsilane successfully proceeded. Mg/Cu-mediated copolycondensation of 1 with 1,6-dibromohexane proceeded to give polymers that have similar compositions to those of random copolymers of ethylene and styrene. (c) 2006 Wiley Periodicals, Inc.

DOI： 10.1002/pola.21637

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Transition metal-mediated copolymerizations of diazocarbonyl compounds with alkynes and an isocyanide were investigated with the following combinations of the comonomers: (E)-1-diazo-3-nonen-2-one (1a) with phenylacetylene (2a), (E)-1-diazo-4-phenyl-3-buten-2-one (1b) with 1-heptyne (2b), ethyl diazoacetate (1c) with 2a and 2b, and 1b with tert-butyl isocyanide (3). All the copolymerizations afforded random copolymers whose GPC traces were unimodal, and H-1 NMR spectra exhibited superposition of signals derived from the repeating units of both comonomers. In addition, the progress of the copolymerizations was supported by the DSC analyses of the products.

DOI： 10.1021/ma0607822

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

The cationic polymerization of isobutyl vinyl ether was examined with transition-metal ate complexes with trityl cation as initiators. The initiators were generated by the reaction of triphenylmethyl chloride [trityl chloride (TrCl)] with ate complexes of Nb, Mo, and W with lithium cation, which were obtained in situ by the reaction of the transition-metal halides with anionic reagents (organolithium or lithium amide). When the polymerization was initiated with a mixture of TrCl and Li+[NbH5(NnBuPh)](-), the resulting poly(isobutyl vinyl ether)s had narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight = 1.13-1.20). Although the polymerization was supposed to be initiated by the electrophilic attack of the trityl cation, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of the resulting poly(isobutyl vinyl ether)s revealed the presence of H at the alpha-chain end. (c) 2006 Wiley Periodicals, Inc.

DOI： 10.1002/pola.21383

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

We report here synthesis and secondary structure of star-shaped polymers composed of poly (ethylene glycol) or poly (ethylene glycol) methacrylate and poly (glutamic acid) derivatives on the phosphazene core (PEPBLG and PEMBLG). The ring-opening polymerization of NCA of γ-benzyl-L-glutamate with PEPA or PEMK gave star-shaped polymers (Mn=13000-27000). From the spectroscopic data (1H NMR, CD and IR) of PEPBLG and PEMBLG, it appears that the polyglutamate chains take α-helical conformation.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

We carried out polymerization of various cyclic diazocarbonyl compounds using palladium metal complexes as initiators to prepare new poly(substituted methylene)s, whose main chains were composed of one of the carbons in the cyclic structures. Although homopolymerization of monomer 1 and 2 did not proceed, their copolymerization with acyclic diazoketones gave copolymers with various compositions. On the other hand, homopolymerization of monomer 3 afforded a polymer with Mn=1110 in a 36.4% yield. Copolymerization of 3 with 1-diazo-3-nonen-2-one 5 gave copolymers, whose compositions corresponded to the feed ratios of the comonomers. Poly3 and copolymers of 3 have unique structures, bearing cyclohexenone rings as substituents. Chemical modification of the polymers will be examined by the reaction with various nucleophiles or anionic growing polymer chain ends.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Recently we have reported that Pd-mediated polymerization of various diazocarbonyl compounds gave poly(substituted methylene)s, which have ester or acyl groups on all the main chain carbon atoms. In this report, the use of organoaluminum compounds as an initiator in place of Pd-compound was examined. The polymerization of (E)-1-diazo-3-nonen-2-one 1 was initiated with 1Bu3Al to give acyl-substituted polymethylenes (poly1) in 41.6% yield. (E)-1-diazo-4-phenyl-3-buten-2-one 2 was polymerized to give poly2 with M n= 1170 in a 30.3% yield. 1H-NMR of the polymer suggested that the side chain acyl groups were partially cleaved to afford unsubstituted CH2n units in the main chain. The degree of the cleavage varied with the kind of R3Al and the feed ratio of the monomer to R3Al.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

We have reported that anionic polymerization of MMA initiated with transition-metal ate complexes of Nb, Mo, W, where the tacticity of resulting PMMAs depends on the structure of transition metal ate complexes and a highly isotactic PMMA can be obtained by the use of appropriate combination of metal element and ligands. In this report, we will present that the YCl 3/1R2RN/nBuLi systems polymerize MMA in a living manner in THF -78 °C. In addition, anionic block copolymerization of MMA and zBA using the Y ate complexes proceeded to give Poly (MMA-b-tBA) in a living manner.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Cyclophosphazenes with six or more reactive sites are useful to prepare star-shaped polymers. We report here the synthesis and secondary structure of star-shaped polyamino acid block copolymers on the phosphazene core (s-PCLL-e-PBLG). The polymer was prepared by the ring-opening polymerization of NCA of Nε-Z-L-Lysine with benzylamine group attached to the phosphazene core, followed by the polymerization of NCA of γ-benzyl-L-glutamate using end amino groups of hexaarmed poly-L-lysine (s-PCLL). The block copolymer (s-PCLL-b-PBLG) (Mi = 58000) has a narrow molecular weight distribution, Mw/Mn = 1.04. The CD spectra exhibited a negative curve at 222 nm, suggesting that most of the block copolymer chains diverging from the core take mainly a right-handed α-helical structure.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Improvement of physical properties of vinyl polymers is expected by incorporating norbornene framework into the main chain. Although copolymerizations of various vinyl monomers with norbornene derivatives have been reported, copolymerization using 2-alkoxycarbonyl norbornenes as a comonomer has never been examined to our knowledge. Herein, we will present a new synthetic procedure for methyl 2-norbornene-2-carboxylate (NB-CO 2Me), and radical Copolymerization of NB-CO2Me with alkyl acrylates and other polar monomers.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Poly(substituted methylene)s are the polymers whose C-C main chains consist of one carbon repeating unit. We have reported that poly(substituted methylene)s can be prepared from alkyl diazoacetates as monomers via Pd-mediated polymerization releasing dinitrogen. In this report, we will present the synthesis of new poly(substituted methylene)s in which all main chain carbons have a phenyl group, using α, α-dibromotoluene as a monomer. The monomer was reacted with excess Mg in THF at 0°C to room temperature for 20h, giving a polymeric product as yellow powder after purification with recycling preparative GPC. Elemental analysis, UV, and fluorescence spectra of the product indicated that it was a poly(phenyl methylene) with C=C double bonds in the main chain, which were successfully brominated by the reaction with Br2. We examined the use of α, α-dibromotoluene as a monomer for Cu-catalysed polycondensation of 1,6-dibromohexane, which was reported by T. Yamamoto et. al. The successful incorporation of the phenylmethylene units into the polymethylene framework was confirmed by analyses of the copolymer samples fractionated by preparative GPC.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

We carried out polymerizations of diazocarbonyl compounds by various metal complexes with several ligands as initiators, and investigated the effect of the ligands on the metal center and the addition of amines or Grignard reagents as additives on the polymerization behavior. Polymerization of the monomer 1 was carried out in THF at 50°C for 13h. We found that molecular weights of the polymers depended on the kind of ligand on palladium center as shown in Table 1. Higher molecular weight polymers were obtained by the use of iPrPhNH and pyridine as an additive (run4, 6, 7, 10). In particular, PdCl 2(2-Me-IMD)2 was most effective at giving high molecular weight polymers(run15). Polymerization initiated by other transition metals and polymerization of other monomers than 1 will also be reported.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

We report here synthesis and secondary structure of star-shaped polymers composed of poly (ethylene glycol) and poly (glutamic acid) derivatives on the phosphazene core (PEPBLG). The initiator was prepared as follows. Hexachlorocyclotriphosphazene was reacted initially with the sodium salt of APEG to yield the intermediate (PPEG), and then PPEG was successively reacted with HMDA-monoBoc to give PEPAB. The initiator PEPA was prepared by the deprotecting of PEPAB. The ring-opening polymerization of NCA of y-benzyl-L-glutamate with PEPA gave star-shaped polymers with narrow molecular weight distribution. The CD spectra of PEPBLG showed negative peaks at 208 and 222nm, indicating that the polymer chains take α-helical conformation.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

As a novel synthetic strategy for poly(vinyl alcohol) and copolymer of vinyl alcohol, we propose homopolymerization of alkoxyvinylsilanes and copolymerization of alkoxyvinylsilanes with other vinyl monomers, followed by oxidative cleavage of alkoxysilyl groups attached to main chain of the resulting polymers. Radical polymerization of di(iso-butoxy)methylvinylsilane1 afforded poly1. The oxidative cleavage of the alkoxysilyl groups in poly1 with m-chloroperbenzoic acid afforded insoluble product, which was characterized by elemental analysis and IR. We presumed that the product was cross-linked poly(vinyl alcohol). Radical polymerization of di(iso-butoxy)methylvinylsilane1 with styrene afforded poly(1-ran-styrene)s with a variety of compositions of both repeating units, although the Mns(&lt
9000) and yields(&lt
35%) were rather low. The oxidative cleavage of the alkoxysilyl groups in poly(1-ran-styrene) with m-chloroperbenzoic acid proceeded efficiently, giving poly(vinyl alcohol-ran-styrene)s, which were soluble in common organic solvents. The structure of poly(vinyl alcohol-ran-styrene)s were characterized by NMR, GPC, elemental analysis, IR, and matrix-assisted laser desorption time-of-flight mass spectrometry(MALDI-TOF-MS).

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Synthesis and fluorescence behaviors of Eu3+ ion complexed with polymethacrylate carrying K salt of 4-carboxyphenoxycyclotriphosphazene side group are studied. The multi-armed monomer EPHEMA was prepared from hexachlorocyclotriphosphazene and HEMA, followed by replacement of P-Cl group by HO-C6H4-COO-C2H5. The polymerization of EPHEMA with AIBN afforded PEPHEMA (Mn=25000-402000). The hydrolysis of PEPHEMA gave PKPHEMA without -CO-OCH2CH2- bond scission. The strong fluorescence at 613nm was observed when [Eu 3+]/[KPHEMA]=0.5 was used (λ ex=260nm).

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Cross-linked polymer particles were prepared by dispersion polymerization using amphiphilic block copolymers with functional groups, hydroxyl or amino groups, as stabilizers which were prepared by ATRP. Obtained particles were modified by hydrolysis and grafted PBLG or liquid crystal polymer (PA6CB). Dispersibility of these particles for some solvents and effects for liquid crystal were studied.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Block copolymers containing poly(β-phenetyl-L-aspartate) (PPLA) and polystyrene (PS) in which PS was connected at N-terminus (PPLA-b-PS) and C-terminus (PS-b-PPLA) of PPLA segment were synthesized, respectively. PPLA-b-PS showed an irreversible conformational transition from right-handed helix to left-handed helix and a reversible rearrangement of PPLA segment on heating as well as PPLA homopolymer in DSC measurement. On the other hand, PS-b-PPLA showed two irreversible transitions with reduction of their temperature by 20°C and transformed to β-structure in the high temperature region.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Synthetic gels are current attention. Despite the interesting application of synthetic gels, their structure is usually poorly controlled. We discuss a new synthesis of polystyrene gels. Molecular weight between cross-linking points and the number of arms at the points in polystyrene gels were regulated by atom transfer radical polymerization and atom transfer radical coupling reaction. Conventional preparation of gels was compared.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Block copolymers containing PS and PBLG were prepared by combination of ATRP and ring-opening polymerization of BLG-NCA. When PS was attached to N-terminus of PBLG helix of the PBLG was transformed to random coil with addition of TFA in CDC13 solution, which determined by 1H NMR, in accordance with PBLG homopolymer. PS-b-PBLG in which C-terminus of PBLG attached to PS, started helix-coil transformation at lower concentration of TFA.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

The anionic polymerization of methyl methacrylate in toluene at -78 degrees C with lithium amides of various secondary amines (diisopropylamine, N-isopropylaniline, N-n-butylaniline, indoline, and N-ethyl-o-toluidine) as initiators was studied. The tacticity of the resulting poly(methyl methacrylate)s (PMMAs) was dependent on the kind of secondary amine, and highly isotactic PMMAs (91-93% mm) were obtained when lithium amides of N-isopropylaniline and N-n-butylaniline were employed. The isotacticity of the PMMAs further increased up to 98% mm with initiating systems composed of the lithium amides, n-butyllithium, and transition-metal halides (WCl6, MoCl5, and NbCl5). (c) 2005 Wiley Periodicals, Inc.

DOI： 10.1002/pola.20912

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Benzyne generated from fluoride-induced reaction of o-trimethylsilylaryl triflates was found to be copolymerized with pyridine to give novel alternating copolymers bearing o-phenylene and 2,3-dihydropyridine units in the main chain. The unique polymer structures were confirmed from the elemental analyses, MALDI-TOF-MS, and IR, although H-1 NMR spectra of the polymers did not exhibit the signals of protons on the pyridine-derived rings. The copolymers obtained as HCl adducts of pyridine-derived rings can be converted to neutral forms via treatment with NaOH aqueous solution, where nucleophilic attack of hydroxide anion to the pyridine-derived rings resulted in the incorporation of hydroxy and imine groups on the cyclic structure. The mechanism of the copolymerization and the transformation with the alkaline treatment thereafter was proposed. This is the first example that benzyne generated from o-trimethylsilylaryl triflates can be used as a monomer for polymerization.

DOI： 10.1021/ma048668b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Palladium-mediated polymerization of diazoketones (1a, 2a, 3a, 4a, and 6a) proceeded to give poly(acylmethylene)s (1b, 2b, 3b, 4b, and 6b), in which all of the main chain carbons had acyl groups. The structures of the novel polymers were characterized by NMR spectroscopy, elemental analyses, and molecular weight measurements (GPC and VPO), where the results of the elemental analyses suggested incorporation of a small amount of azo group (-N=N-) into the main chain (ca. one -N=N- per polymer chain). The presence of a C=C double bond adjacent to the carbonyl carbon in the monomers was required for the polymerization to proceed. Palladium-mediated copolymerizations using a variety of combinations of diazoketones and ethyl diazoacetate, 8, as comonomers proceeded to give various poly(substituted methylene)s.

DOI： 10.1021/ma048293u

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Block copolymerization of poly(β-phenetyl-L-aspartate) (2PLA) with polystyrene (PS) were successfully carried out by combination of ATRP and NCA method, and obtained 2PLA-b-PS and PS-b-2PLA,in which PS was bonded at N-terminus and C-terminus of 2PLA, respectively. 2PLA-b-PS showed thermally reversible helix-helix transition as well as 2PLA homopolymer in tetrachloroethane which was determined by 1H NMR, while its temperature from right handed helix (PH) to left handed helix (LH) was lower than that of 2PLA homopolymer by 20°C. In PS-b-2PLA, on the other hand, not only PH but also LH already existed at room temperature and transformed into another conformation without helix and random above 70°C which was denoted by appearance of new NH signal at 8.4 ppm. This study clearly shows that each terminus of 2PLA homopolymer has a different role in helix-helix transition.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

There has been considerable interest in inorganic-organic hybrid polymers with cyclotriphosphazenes, as side groups on carbon main chains. These polymers may provide a new type of materials since the properties and functionalities of polymers can easily be modified by organic groups. We report here the polymerization of methyl acrylates with phenoxycyclotriphosphazene groups, which were prepared from hexachlorocyclotriphosphazene and HEMA, followed by the replacement of P-C1 group by organic units such as 4-hydroxybenzaldehyde and 4-bromophenol. In 1H-NMR spectra of the polymers prepared by radical polymerization, the peak assignable to methylene proton in the main chain was not observed, suggesting that the main chain is surrounded with bulky cyclotriphosphazene groups. As expected, qualitative test of flame retardance indicates that polymers have self-extinguishing properties. Characteristic features and thermal behaviors of polymers will be reported.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Pd-mediated Copolymerization of diazocarbonyl compounds with phenyldiazomethane was examined. The PdCl2/pyridine system was found to be effective for the copolymerization of ethyldiazoacetate with phenyldiazomethane, giving copolymers with the composition expected from the feed ratio of the comonomers. Elemental analyses of the products suggested that azo group (-N=N-) derived from the monomers was incorporated into the main chain, where the presence of the azo group was comfirmed by Raman spectroscopy. When ethyl diazoacetate was employed as a diazocarbonyl compound, the Pd 2(dba)3/pyridine system was effective to give copolymers. Homo polymerization of phenyldidazomethane mediated by the Pd 2(dba)3/pyridine system gave poly(phenylmethylene)s having azo group in their main chain.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Cationic polymerization of isobutylvinylether (IBVE) was examined by using transition metal ate complexes as initiators. We have found that ate complexes prepared from transition metal halide, Ph3CCI, lithium amide, and nBuLi can initiate the polymerization. In particular, an ate complex of Nb Ph3C+[Nb(nBuPhN)H5]- gave a poly(IBVE) with narrow molecular weight distribution (MWD) (Mn=6000, M w/Mn=1.12) by the polymerization in toluene at r.t. for 62.5h in 60.3%. The polymerization was accelerated by raising the reaction temperature to 40 or 50°C, where the obtained polymers still had narrow MWDs. Poly(IBVE)s with narrow MWDs were not obtained, when ate complexes with different compositions of nBuPhN and H as ligands, and Mo or W as a metal center were employed. MALDI-TOF-MS analysis revealed the chain end structure of the poly(IBVE)s obtained with Ph3C+[Nb(nBuPhN)H 5]-.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Recently our laboratory reported synthesis of poly (substituted methylenes) by palladium-mediated polymerization of alkyl diazoacetates. The obtained polymers have an ester group on every carbon atom of the main chains. In this report, diazoketone compounds are used as monomers for the Pd-mediated polymerization. The polymerization of (E)-1-diazo-3-nonene-2-one was initiated with PdCl2 (MeCN)2 to give acyl-substituted polymethylenes (poly) in 49.6% yield. The structure of the new polymer was characterized by 1H-NMR, GPC, and elemental analysis. The polymerization of (E)-1-diazo-4-phenyl-3-buten-2-one initiated with PdCl2 (MeCN) 2 gave a high molecular weight poly in good yield. The presence of C=C double bond adjacent to the carbonyl carbon in the monomer was required for the polymerization to proceed. Palladium-mediated copolymerization using a variety of combinations of diazoketones and ethyl diazoacetate as comonomers proceeded to give various poly (substituted methylene) s.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Poly (substituted methylene)s are the polymers whose C-C main chains consist of one carbon repeating unit. We have reported that poly (substituted methylene)s can be prepared from alkyl diazoacetates as monomers via Pd-mediated polymerization releasing dinitrogen. In this report, we will present the synthesis of new poly (substituted methylene)s in which all main chain carbons have a phenyl group, using α, α -dibromotoluene as a monomer. The monomer was reacted with excess Mg in THF at 0°C to room temperature for 12h, giving a polymeric product as yellow powder after purification with recycling preparative GPC. Elemental analysis, UV and fluorescence spectra, and MALDI-TOF-MS of the product indicated that it was a poly (phenyl methylene) with C=C double bonds in the main chain, which were successfully brominated by the reaction with Br2. The brominated polymer generated cationic charges by the reaction with Me3Al and it reacted with IBVE, giving a graft copolymer. Furthermore, the use of Me2SiCl2 as a comonomer for the polymerization was effective to prepare higher molecular weight polymer.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Amphiphilic block copolymers (PS-b-PAMS) containing polystyrene (PS) and poly(aminomethylstyrene) (RAMS) with various degrees of polymerization (DP) and compositions were used as stabilizers for dispersion polymerizations of styrene or divinylbenzene (DVB), leading polymer nanoparticles with a lot of amino groups on their surfaces. Diameter of PS particle was around 1 μm when DP of PS segment (DPPS) and RAMS segment (DPPAMS) were 20 and 80, respectively. The diameter became shorter with increment of DPPS, which indicates that flocculation and coalescence of the particles were kept out of their polymeric kinetics. PDVB particles were obtained as well as PS particles. The amino groups on their surfaces were changed to ammonium chloride or polypeptide and we observed their variable dispersibility in some solvents.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Benzyne generated from fluoride-induced reaction of o-trimethylsilylaryl triflates was found to be copolymerized with pyridine to give novel alternating copolymers bearing o-phenylene and 2,3-dihydropyridine units in the main chain. The unique polymer structures were confirmed from the elemental analyses, MALDI-TOF-MS, and IR, although 1H NMR spectra of the polymers did not exhibit the signals of protons on the pyridine-derived rings. The copolymers obtained as HCl adducts of pyridine-derived rings can be converted to neutral forms via treatment with NaOH aqueous solution, where nucleophilic attack of hydroxide anion to the pyridine-derived rings resulted in the incorporation of hydroxy and imine groups on the cyclic structure. The mechanism of the copolymerization and the transformation with the alkaline treatment thereafter was proposed. This is the first example that benzyne generated from o-trimethylsilylaryl triflates can be used as a monomer for polymerization.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Cyclophosphazenes with six or more reactive sites are useful to prepare star-shaped polymers. We report here the synthesis and conformation of hexaarmed amphiphilic polyglutamic acids on the phosphazene core (6p6-PLG). The polymer was prepared by the ring-opening polymerization of NCA of γ-benzyl-L- glutamate with benzoylaminohexylamine attached to the phosphazene core. The six amino groups in the initiator participate in the polymerization without delay, and the hexaarmed polyglutamate formed takes α-helical structure. The pH dependence of 6p6-PLG showed that upon a pH decrease, the helix content increases first rapidly in the pH range from ∼5.0 to ∼4.5, and then slowly in the pH range from ∼4.0 to ∼3.5.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Amphiphilic block copolymer containing polystyrene (PS) and poly[(2-hydroxyethyl)methacrylate] (PHEMA) segments was used as a stabilizer for dispersion polymerization of styrene (S) or divinylbenzen (DVB). Size of obtaining PS particles (0.7μm-2.5μm) was controllable with degree of polymerization (DP) and composition of the block copolymer. Flocculation and resulting coalescence of particles were observed with adding DVB to S in the dispersion polymerization. These results mean that the size of the PS particles was owing to their flocculation and coalescence. However, spherical polyDVB particles could not be obtained even if DP of PHEMA segment was 400 and concentration of DVB was decreased to 5 wt% in order to prevent them from the flocculation. On the other hand, post addition of DVB to PS particles could prepare cross-linked particles without flocculation. Hydroxyl groups on their surface were converted in liquid crystalline polymers by ATRP. Effects of the surface exchange were investigated.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

We have reported that transition metal ate complexes can initiate anionic polymerization of MMA. For example, the WCl6/PhLi/iBu3Al systems polymerize MMA in a living manner, affording high molecular weight PMMAs with narrow molecular weight distribution. In this report, we will present that the YCl3/1R2RN/nBuLi systems polymerize MMA in a living manner in THF -78 °C. Also, anionic block copolymerization of MMA and nBA using the Y ate complexes proceeded to give PMMA-b-P(nBA) in a living manner. In addition, we will present the results of MMA polymerization initiated with transition metal ate complexes of Nb, Mo, W, where the tacticity of resulting PMMAs depends on the structure of transition metal ate complexes and a highly isotactic PMMA can be obtained by the use of appropriate combination of metal element and ligands.

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Language：Japanese   Publisher：The Society of Polymer Science, Japan  

DOI： 10.1295/kobunshi.53.598

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The combination of potassium tert-butoxide (tBuOK) and triisobutylaluminum (iBU(3)Al) (the tBuOK/iBU(3)Al system) initiated the anionic polymerization of tert-butyl acrylate (tBA) and methyl methacrylate (MMA) and controlled the polymerization with respect to molecular weights and molecular weight distributions (MWDs). Poly(tBA)s (M-n = 20 000-80 000) with narrow MWDs (M-w/M-n = 1.05-1.12) were obtained quantitatively in toluene at 0 degreesC for 1-2 h. The controlled character of the polymerization remained intact even at high temperatures up to 50 degreesC. MALDI-TOF-MS analyses of a low molecular weight poly(tBA) prepared with the initiating system revealed that the polymer had hydrogens at both chain ends. Block copolymerizations of tBA and MMA were also successful in toluene at 0 degreesC by using the initiating system, giving poly(tBA-b-MMA)s with various compositions of the two monomer units and narrow MWDs in high yield. Although the tBuOK/iBu(3)Al system failed to control the homopolymerization of MMA in toluene or THF, the use of diethyl ether (Et2O) as a solvent for the polymerization coupled with cesium fluoride (CsF) resulted in the quantitative formation of high molecular weight poly(MMA)s with narrow MWDs.

DOI： 10.1021/ma030582f

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The thermal stability and degradation behavior of polystyrene (PSt) and poly(methyl methacrylate) (PMMA) blended with organic cyclotriphosphazenes (N3P3(OR)(6)) were investigated by thermogravimetric analysis and gel permeation chromatography. The thermal degradation behaviors of polymers are strongly dependent on the organic groups attached to the phosphazene ring (R: S-4,-C6H3(-OCH2O-); S-5,-C6H4CH2OPO(OPh)(2); S-6,-C6H4OPO(OPh)(2); S-7,-C6H4OCH2OCH3). The onset temperature of decomposition (T-0) of PSt increased from 303 degreesC to 351 degreesC in air by the addition of 5 wt.% S-4, whereas S-6 has no ability to increase T-0 value of Psi. The GPC traces of PSt/S-4 film heated at 180 degreesC for 30 min in air showed no significant decrease of molecular weight of Psi. A similar enhancement of thermal stability was observed for the PMMA/S-4 system. From the reaction of radical initiators with S-4 it appears that -OCH2O- group in S-4 acts as an effective trapping site of peroxy radical. As expected, the physical loss of S-4 with molecular weight increased by using cyclotriphosphazene core from PSt film was significantly suppressed, i.e.. the diffusion coefficient of S-4 was three orders of magnitude smaller than that of 3,4-methylenedioxyphenol (MOP). The enhancement of thermal stability of PSt and PMMA blended with cyclotriphosphazene derivatives were described. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymdegradstab.2003.09.015

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Anionic polymerization of methyl methacrylate (MMA) in the presence of divalent transition metal halide (MX2 = FeBr2, MnCl2, CoCl2, NiBr2) was investigated. Initiating systems with various combinations of MX2, lithium diphenylamide (Ph2NLi), and organolithium (RLi, where R = nBu, Me) were effective to giving a high yield of poly(methyl methacrylate)s (PMMAs) at -78 degreesC in toluene. The tacticity of the resulting PMMAs was highly dependent on the combination of the reagents used for the generation of the initiating systems within a syndiotactic (rr = 59%) to isotactic (mm = 65%) range. (C) 2003 Wiley Periodicals, Inc.

DOI： 10.1002/pola.10986

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Anionic polymerization of methyl methacrylate (MMA) initiated with late transition-metal halides [manganese chloride (MnCl2), iron dichloride (FeCl2), iron trichloride (FeCl3), cobalt chloride (CoCl2), or nickel bromide (NiBr2)]/organolithium [nButyllithium (nBuLi) or phenyllithium (PhLi)]/triisobutylaluminum (iBu(3)Al) systems is described. Except for the system with NiBr2, the polymerizations of MMA afforded narrow molecular weight distribution poly(methyl methacrylate)s (PMMAs) with high molecular weights in quantitative yields at 0 degreesC in toluene. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses of the PMMAs obtained by the systems with FeCl2, FeCl3, and CoCl2 revealed that the polymers had hydrogen (H) at both chain ends. Accordingly, the reaction of the transition-metal halides with the organolithium in the presence of iBu(3)Al should result in the formation of transition-metal hydride [M-H](-) species, which was nucleophilic enough to initiate the MMA polymerization. Because the presence of a six-membered cyclic structure resulting from backbiting was confirmed from the MALDI-TOF MS analyses of the PMMA obtained with the metal halide (FeCl2, FeCl3, or CoCl2)/organolithium systems in the absence of iBu(3)Al, the introduction of H at the omega-chain end indicated that iBu(3)Al should prevent the backbiting. However, the MnCl2/nBuLi/iBu(3)Al initiating system gave PMMAs bearing H at the a chain end and six-membered cyclic structure at the omega chain end. (C) 2003 Wiley Periodicals, Inc.

DOI： 10.1002/pola.10737

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER-VERLAG  

The presence of Cr(CO)(6) in nBuLi-initiated anionic polymerization of methyl methacrylates (MMA) was found to effectively enhance stereoselectivity of the polymerization in toluene at 0degreesC. nBuLi/Cr(CO)(6) afforded an isotactic PMMA with 86 % of mm triad, and the polymers obtained with nBuLi/Cr(CO)(6)/tBuOK were rich in heterotactic structures (mr = ca. 54%). In both cases, the selectivity was improved in ca. 10% compared to those of the polymerization conducted under the similar conditions without Cr(CO)(6).

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The preparation of star-shaped poly(gamma-benzyl-L-glutamate)s by the ring-opening polymerization of N-carboxy anhydride gamma-benzyl-L-glutamate (BLG-NCA) with hexakis(4-aminomethylphenoxy)- (4) and hexakis(4-aminophenoxy)cyclotriphosphazenes (6), and the conformation of resulting polymers has been studied. The six amino groups in 4 can initiate the polymerization of BLG-NCA to give star-shaped polyglutamates (7) with narrow molecular weight distributions ((M) over bar (w)/(M) over bar (n) = 1.10-1.33). For the polymerization of BLG-NCA with 6, however, a high ratio of [BLG-MCA]/[6] was required to obtain star-shaped polyglutamates (8), The conformation of 7 changed from a beta-sheet form to a right-handed alpha-helix form, depending on the degree of polymerization per chain (DP) over bar (n)/6). The helix content of hexa-armed poly (gamma-benzyl-L-glutamate-CO-L-glutamic acid)s (9), prepared by partial hydrolysis of 7, increased significantly compared with that of the corresponding linear analogue (10). As increasing of helix content of 9, the fluorescence spectra of 8-amilino-1-naphthalenesulfonic acid (ANS), a fluorescence probe, shifted to a short wavelength accompanied by the enhancement of intensity, suggesting that star-shaped polymers are liable to form hydrophobic domains. From these results and the structural feature of the cyclotriphosphazene core, the formation of a 3alpha-helix bundle structure of polyglutamates on both sides of the phosphazene ring has been suggested.

DOI： 10.1002/mabi.200390002

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Polymerization of alkyl diazoacetates [N2CHCO2R: R = Et (1a) and Me (1b)] mediated by PdCl2 in the presence of an amine gave poly(alkoxycarbonylmethylene)s [(CHCO2R)(n): R = Et (2a,b), Me (3a,b)] bearing an ester group on every carbon atom of their main chains. MALDI-TOF-MS analyses of the polymers 2a and 3b indicated that the degree of polymerization of the polymers extended up to nearly 100, The Pd-mediated polymerization of 1a and 1b in the presence of pyridine afforded the polymers quantitatively after reprecipitation from CHCl3 into n-hexane. A mechanism of the polymerization initiated with a Pd-assisted nucleophilic attack of an amine to the monomers is proposed.

DOI： 10.1021/ma021169v

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

Anionic polymerization of methyl methacrylate (MMA) was initiated with chromium and vanadium ate complexes generated by the reaction of transition metal trichloride (MCl3: M = Cr, V) with n equiv of lithium diisopropylamide (LDA) (n = 1-3) and 4-n equiv of phenyllithium (PhLi). The MCl3/n LDA/4-n PhLi systems were capable of polymerizing MMA in a living manner in tetrahydrofuran (THF) at -78degreesC, giving poly(methyl methacrylate)s (PMMA) with narrow molecular weight distributions (MWD) in high yield, where the number-average molecular weight (Mn) of the PMMAs increased proportionally with monomer to initiator feed ratio. Matrix-assisted laser desorption inonization time-of-flight mass spectrometry (MALDI-TOF-MS) revealed that the anionic polymerization was initiated by the nucleophilic attack of diisopropylamide (iPr(2)N(-)) group on the transition metal center of the ate complexes and the growing species was stable under the polymerization conditions.

DOI： 10.1295/polymj.35.972

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Molybdenum chloride (MoCl5 or 1a) and tungsten chloride (WCl6 or 1b)/phenyllithium (PhLi)/triisobutylaluminum (iBu(3)Al) systems were found to be quite effective for controlling the anionic polymerization of methyl methacrylate (MMA), affording high molecular weight poly(methyl methacrylate)s (PMMAs; number-average molecular weight &gt; 100,000) with narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight &lt; 1.25) quantitatively at 0 degreesC for 1 h in toluene. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses of PMMAs obtained with the 1a and 1b/organolithium (RM; n-butyllithium, PhLi)/iBu(3)Al systems revealed that the initiation of MMA with the systems occurred by a nucleophilic attack of H- to the monomer. In addition, the MALDI-TOF MS analyses indicated that the presence of iBu(3)Al was responsible for the controlled polymerization by improving the uniformity of the polymerization with respect to initiation and termination and by preventing a backbiting reaction. (C) 2002 Wiley Periodicals, Inc.

DOI： 10.1002/pola.10523

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ma020149q

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Organomanganate reagents [R3Mn]Li--(+) (R = Bu, Me) were found to polymerize methyl methacrylate in the presence of potassium tert-butylate. A conversion of the tacticity of the resulting poly(methyl methacrylate)s from heterotactic (mr = 54%) to isotactic (mm = 58%) was observed upon changing the R group of the initiator from Bu to Me. The addition of triisobutylaluminium was found to efficiently control (M) over bar (w) and (M) over bar (w)/(M) over bar (n) of the resulting polymers.

DOI： 10.1002/1521-3927(20020101)23:1<64::AID-MARC64>3.3.CO;2-D

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The synthesis, structures, and reactivity of cationic aluminum complexes containing the N,N'-diisopropylaminotroponiminate ligand (Pr-i(2)-ATI(-)) are described. The reaction Of ( Pr-i(2)-ATI)AIR(2) (1a-e,g,h; R = H (a), Me (b), Et (c), Pr (d), Bu-i (e), Cy (g), CH2Ph (h)) with (Ph3C][B(C6F5)(4)] yields (Pr-i(2)-ATI)AlR+ species whose fate depends on the properties of the R ligand. la and lb react with 0.5 equiv of [Ph3C][B(C6F5)(4)] to produce dinuclear monocationic complexes [{(Pr-i(2)-ATI)AlR}(2)(mu -R)][(C6F5)(4)] (2a,b). The cation of 2b contains two (Pr-i(2)-ATI)AIMe+ units linked by an almost linear Al-Me-Al bridge; 2a is presumed to have an analogous structure. 2b does not react further with [Ph3C][B(C6F5)(4)]. However, 1a reacts with 1 equiv of [Ph3C][B(C6F5)(4)] to afford (Pr-i(2)-ATI)Al(C6F5)(mu -H)(2)B(C6F5)(2) (3) and other products, presumably via C6F5-transfer and ligand redistribution of a [(Pr-i(2)-ATI)AlH][(C6F5)(4)] intermediate. 1c-e react with 1 equiv of [Ph3C][B(C6F5)(4)] to yield stable base-free [(Pr-i(2)-ATI)AlR][B(C6F5)(4)] complexes (4c-e). 4c crystallizes from chlorobenzene as 4c(CIPh).0.5PhCl, which has been characterized by X-ray crystallography.
In the solid state the PhCl ligand of 4c(ClPh) is coordinated by a dative PhCl-Al bond and an ATI/Ph T-stacking interaction. 1g,h react with [Ph3C][B(C6F5)(4)] to yield (Pr-i(2)-ATI)Al(R)(C6F5) (5c,h) via C6F5- transfer of [(Pr-i(2)-ATI)AlR][(BC6F5)(4)] intermediates. 1c,h react with B(C6F5)3 to yield (Pr2-ATI)Al(R)(C6F5) (5c,h) via C6F5- transfer of [(Pr-i(2)-ATI)AlR][RB(C6F5)(3)] intermediates. The reaction of 4c-e with MeCN or acetone yields [(Pr-i(2)-ATI)Al(R)(L)][B(C6F5)(4)] adducts (L = MeCN (8c-e), acetone (9c-e)), which undergo associative intermolecular L exchange. 9c-e undergo slow beta -H transfer to afford the dinuclear dicationic alkoxide complex [{(i)(Pr(2)ATI)Al(mu -(OPr)-Pr-i)}(2)][B(C6F5)(4)](2) (10) and the corresponding olefin. 4c-e catalyze the head-to-tail dimerization of tert-butyl acetylene by an insertion/sigma -bond metathesis mechanism involving [(Pr-i(2)-ATI)Al(C dropC' Bu)][B(C6F5)(4)] (13) and [(Pr-i(2)-ATI)Al(CH=C(' Bu)C dropC' Bu)][B(C6F5)(4)] (14) intermediates. 13 crystallizes as the dinuclear dicationic complex [ (Pr-i(2)-ATI)Al(mu -C dropC' BU)](2)][B(C6F5)(4)](2). 5PhCl from chlorobenzene. 4e catalyzes the polymerization of propylene oxide and 2a catalyzes the polymerization of methyl methacrylate. 4c,e react with ethylene-d(4) by beta -H transfer to yield ((Pr-i(2)-ATI)AlCD2CD2H][B(C6F5)(4)] initially. Polyethylene is also produced in these reactions by an unidentified active species.

DOI： 10.1021/ja010242e

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DOI： 10.1002/1521-3935(20010601)202:9<1518::AID-MACP1518>3.0.CO;2-E

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A half-metallocene-type complex, La(C5Me5)[CH(SiMe3)(2)](2)tetrahydrofuran (THF) 1, showed the dual function of performing the controlled polymerizations of nonpolar monomers such as ethylene and styrene as well as polar monomers like methyl methacrylate, hexyl isocyanate, and acrylonitrile in high yields. On the other hand, the metallocene-type rare-earth metal complexes, [(C5H4SiMe3)(2)Y(mu -Me)](2) 2 and (C5Me5)(2)YMe(THF) 3, showed relatively low catalytic activity. The structure of complex 2 was characterized by X-ray analysis. (C) 2001 John Wiley & Sons, Inc.

DOI： 10.1002/pola.1115

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

New trivalent samarium and 5-ytrium complexes with bridging bis(cyclopentadienyl) ligands mere synthesized, and olefin polymerization catalysis of the complexes having an alkyl group [R = CH(SiMe3)(2)] on the metal was investigated. Three types of the rare earth halides (I ac, C-1, and meso) whose structures differed with respect to the bridging group and the positions of substituents on the cyclopentadienyl (Cp) rings were prepared: rac-Sm-Cl, Me2Si[2,4-Me3Si)(2)C5H2](2)SmCl2Li(THF)(2) (1a); C-1-Sm-Cl, Me2Si[2,4-(Me3Si)(2)C5H2][3,4-(Me3Si)(2)C5H2]-SmCl2Li(THF)(2) (2a); C-1(Ph2Si)-Sm-Cl, Ph2Si[2,4-(Me3Si)(2)C5H2][3,4-(Me3Si)(2)C5H2]SmCl2-Li(THF)(2) (3); meso-Sm-Cl, [1,2-(Me2Si)(Me2SiOSiMe2)](4-Me3CC5H2)(2)SmCl2Li(THF)(2) (4a); rac-Y-Cl, Me2Si[2,4-(Me3Si)(2)C5H2](2) YCL2Li(THF)(2) (5a); C-1-Y-Cl, Me2Si[2,4-(Me3Si)(2)C5H2][3,4-(Me3Si)(2)C5H2]YCl2Li(THF)(2) (6a); meso-Y-Cl, [1,2-Me2Si)(Me2SiOSiMe2)](4-Me3SiC5H2)(2)YCl-(THF) (7a). Although the rac and C-1 complexes (1a, 2a and 5a, 6a) were obtained as an isomeric mixture by the reaction of LnCl(3) (Ln = Sm, Y) with a dilithium salt of the ligand Me2Si[(Me3Si)(2)C5H3](2), it could be separated into both the pure complexes by utilizing the difference of solubility in hexane in each case.
Structural data were obtained on Ist, aa, 3, and 7a to confirm the structures expected from NMR spectroscopy. The (ring centroid)metal-(ring centroid) angles in these complexes are ca. 10-20 degrees smaller than those in nonbridging bis(cyclopentadienyl) rare earth complexes. The rare earth halides la, 2a, 4a, 5a, 6a, and 7a reacted with LiCH(SiMe3)(2) to afford rare earth alkyl complexes, rac-Sm-R, Me2Si[2,4-(Me3Si)(2)C5H2](2)SmCH(SiMe3)(2) (1b); C-1-Sm-R, Me2Si[2,4-(Me3Si)(2)C5H2][3,4-(Me-3-Si)(2)C5H2]SmCH(SiMe3)(2) (2b); meso-Sm-R, [1,2-(Me2Si)(Me2SiOSiMe2)](4-Me3CC5H2)(2)SmCH-(SiMe3)(2) (4b); rac-Y-R, Me2Si[2/4-(Me3Si)(2)C5H2](2) YCH(SiMe3)(2) (5b); C-1-Y-R, Me2Si[2,4-(Me3Si)(2)C5H2] [3,4-(Me3Si)(2)C5H2]YCH(SiMe3)(2) (6b); meso-Y-R, and [1,2-(Me2Si)(Me2SiOSiMe2)] (4-Me3SiC5H2)(2)YCH(SiMe3)(2) (7b), respectively. Only C-1 type alkyl complexes (2b and Gb) polymerize ethylene, giving high molecular weight polyethylenes, and the precise structure of the active Sm complex 2b was determined by X-ray crystallography.

DOI： 10.1021/om000226a

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The synthesis and crystal structures of samarium complexes incorporating bridged Cp'-SiMe2-allenyl/propargyl ligands [Cp' = (Me3Si)(2)(C5H2)] are described. The reaction of a dilithium salt of [(Me3Si)(2)(C5H3)]SiMe2CH2C=CSiMe3 (1a) with SmCl3 yielded an eta (3)-allenyl complex ([(Me3Si)(2)(C5H2)]SiMe2(eta (3)-C=C=C[H]SiMe3)} SmCl3Li2(TMEDA)(2) (2a) (TMEDA = N,N,N',N'-tetramethylethylenediamine). On the other hand, the reaction of a dilithium salt of a Ph,Si substituted ligand [(Me3Si)(2)(C5H3)]SiMe2CH2C=CSiPh3 (Ib) with SmCl3 yielded an eta (1)-propargyl complex ([(Me3Si)(2)(C5H2)]SiMe2(eta (1)-CHC=CSiPh3)}-Sm(TMEDA)[Cl2Li(TMEDA)] (2b). A conversion of bonding mode from eta (1)-propargyl to eta (3)-allenyl was observed when 2b was treated with (Me3Si)(3)CLi/LiI to give an eta (3)-allenyl complex ([(Me3Si)(2)(C5H2)]SiMe2(eta (3)-CH=C=CSiPh3)} SmI2Li(TMEDA) (3b). The same structural conversion was also observed when 2b was treated with (Me3Si)(2)CHLi to give an anionic ate complex ({[(Me3Si)(2)(C5H2)]SiMe2(eta (3)-CH=C=CSiPh3)}SMCl[CH(SiMe3)(2)])[Li(TMEDA)(2)] (4b), which had the eta (3)-allenyl bonding structure. The structures of these four complexes (2a, 2b, 3b, and 4b) were revealed by X-ray crystallography. These are the first examples of the structural characterization of eta (3)-allenyl and eta (1)-propargyl lanthanide complexes. (C) 2000 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-328X(00)00479-4

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A series of nickel complexes, including Ni(acac)(2), (C2H5)Ni(eta (3)-allyl), and [NiMe4Li2(THF)(2)](2), that were activated with modified methylaluminoxane (MMAO) exhibited high catalytic activity for the polymerization of methyl methacrylate (MMA) but showed no catalytic activity for the polymerization of ethylene and 1-olefins. The resulting polymers exhibited rather broad molecular weight distributions and low syndiotacticities. In contrast to these initiators, the metallocene complexes (C5H5)(2)Ni, (C5Me5)(2)Ni, (Ind)(2)Ni, and (Me3SiC5H4)(2)Ni provided narrower molecular weight distributions at 60 degreesC when these initiator were activated with MMAO. Half-metallocene complexes such as (C5H5)NiCl(PPh3), (C5Me5)NiCl(PPh3), and (Ind)NiCl(PPh3) produced poly(methyl methacrylate) (PMMA) with much narrower molecular weight distributions when the polymerization was carried out at 0 degreesC. Ni[1,3-(CF3)(2)-acac](2) generated PMMA with high syndiotacticity. The NiR(acac)(PPh3) complexes (R = Me or Et) revealed high selectivity in the polymerization of isoprene that produced 1,2-/3,4-polymer at 0 degreesC exclusively, whereas the polymerization at 60 degreesC resulted in the formation of cis-1,4-rich polymers. The polymerization of ethylene with Ni(1,3-tBu(2)acac), and Ni[1,3-(CF3)(2)-acac](2) generated oligo-ethylene with moderate catalytic activity, whereas the reaction of ethylene with Ni(acac)(2)/MMAO produced high molecular weight polyethylene. (C) 2000 John Wiley & Sons, Inc.

DOI： 10.1002/1099-0518(200012)38:1+<4764::AID-POLA150>3.0.CO;2-B

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Oligomerization of epsilon-caprolactone and delta-valerolactone was performed by use of SmMe(C5Me5)(2)(THF)(2) initiator, and the 26-mer, 28-mar and 30-mer of epsilon-caprolactone were isolated in pure form by preparative SFC. The MALDI-TOF mass spectrum of the 28-mer indicates that the parent peak (3256.1) emerges as 28-mer + 2Na - H (3256.9). The ESI mass spectrum of the 28-mer indicates that the molecular weight (3211.7) is consistent with the calculated value (3211.9). In a similar manner, the 19-, 25- and 32-mers of delta-valerolactone were isolated. The MALDI-TOF mass spectrum of the 19-mer indicates that the parent peaks(1896.6 and 1879.9) emerge as 19-mer + Na + K + MeOH - 1-hexanol-5-one (1896.3) and 19-mer + 2Na + MeOH - 1-hexanol-5-one (1880.2). Glass transition and melting temperatures (T-g and T-m) of oligo-epsilon-caprolactones and oligo-delta-valerolactones increase with increasing degree of polymerization.

DOI： 10.1002/(SICI)1521-3935(19990401)200:4<758::AID-MACP758>3.0.CO;2-B

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A variety of allylic, aza-allylic and 1,5-diazapentadienyllanthanide compounds were synthesized and their polymerization catalysis toward methyl methacrylate were examined. Divalent Sm[1,3-bis(trimethylsilyl)propenyl](2)(THF)(2) 1 and Sm(1,3-diphenylpropenyl)(2)(THF)(2) 2 were synthesized by the reaction of potassium 1,3-bis(trimethylsilyl)propenide or potassium 1,3-diphenyl-propenide with SmI2. The aza-allyllanthanide compound was synthesized by the reaction of 2-pyridylbenzyllithium with SmCl3 followed by the reaction with LiCH(SiMe3)(2) to give (2-pyridylbenzyl)(2)SmCH(SiMe3)(2) 3. 1,5-Diazapentadienyllanthanide was prepared by the reaction of K[(C5H4N)(2)CPh] with YbBr2 to give Yb[(C5H4N)(2)CPh](2)(THF)(2) 4, which crystalizes monoclinic, space group C2/C (No. 15), with a = 35.19(1), b = 13.613(3), c = 26.552(7) Angstrom, beta = 133.77(1)degrees and Z = 8. Preparations of divalent samarium and ytterbium complexes with bis(2-pyridylphenylmethyl)dimethylsilane ligand (6 and 7) were carried out by the reaction of dipotassium salt of bis(2-pyridylphenylmethyl)dimethylsilane with SmI2 or YbBr2. By using the resulting compounds 1, 2, 3, 4, 6 and 7 as initiator, we have examined their catalytic activities for the polymerization of methyl methacrylate and found that compounds 6 and 7 are effective to give high molecular weight isotactic polymers. (C) 1999 Elsevier Science S.A. All rights reserved.

DOI： 10.1016/S0022-328X(98)00977-2

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The 1:1-2:1 reaction of [2,6-((PrO)-Pr-i)(2)C6H3]Li with anhydrous SmCl3 in THF gave [2,6-((PrO)-Pr-i)(2)C6H3](3) Sm 1 exclusively, while the 3:1 reaction gave [2,6-((PrO)-Pr-i)(2)C6H3](4)SmLi 2 as major product, which crystallizes in the monoclinic space group C2/c(No. 15) with a = 47.52(1) Angstrom, b = 11.680(9) Angstrom, c = 18.862(9) Angstrom, beta = 112.19(3)degrees, V= 9694(8) Angstrom(3), Z = 8, R = 0.077 and R-w = 0.074. In a similar manner, [2,6-((PrO)-Pr-i)(2)C6H3](3)La was obtained by reacting with LaCl3(THF)(2). The 2:1 reaction of [2,6-((PrO)-Pr-i)(2)C6H3]Li with YbCl3 gave [2,6-((PrO)-Pr-i)(2)C6H3](2)YbCl, which produces [2,6-((PrO)-Pr-i)(2)C6H3]Yb-2[CH(SiMe3)(2)](2)Li 4 by reaction with (SiMe3)(2)CHLi. Polymerizations of epsilon-caprolactone and alkyl isocyanates were examined using the resulting complexes. (C) 1998 Elsevier Science S.A. All rights reserved.

DOI： 10.1016/S0022-328X(98)00783-9

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DOI： 10.1021/ja9817444

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

This paper deals with the preparation and olefin polymerization catalysis of six new divalent samarium complexes. These bridged bis(cyclopentadienyl) (Cp) complexes exhibit various structures with regard to the bridging group and the position of substituents on the Cp rings: rac-tBu, Me2Si(2-Me3Si-4-tBuC(5)H(2))(2)Sm(THF)(2) (7); rac-tBuMe(2)Si, Me2Si(2-Me3Si-4-tBuMe(2)SiC(5)H(2))(2)Sm(THF)(3) (8); C-1 symmetric, Me2Si[2,4-(Me3Si)(2)C5H2][3,4-(Me3Si)(2)C5H2]-Sm(THF)(2) (9); meso, [1,2-(Me2Si)(Me2SiOSiMe2)](3-tBuC(5)H(2))(2)Sm(THF)(2) (10); C-2v symmetric (Ph2Si), Ph2Si[3,4-(Me3Si)(2)C5H2](2)Sm(THF)(2) (11); C-2v symmetric [(SiOSi)(2)], [1,2-(Me-2-SiOSiMe2)(2)](3-tBuC(5)H(2))(2)Sm(THF)(2) (12). The structures of 7, 8, 10, and 12 were confirmed by X-ray crystallographic analysis. Among these divalent complexes, meso type complex 10 showed the highest activity for polymerizations of ethylene (5 x 10(5) g of PE/(mol h)) and C-1-symmetric 9 afforded the highest molecular weight of polyethylene (M-n = 145 x 10(4)). Only racemic complexes 7 and 8 could polymerize l-olefins such as l-pentene and l-hexene, giving highly isotactic polymers. Moreover, rac-7 induces catalytic cyclopolymerization of 1,5-hexadiene to give poly(methylene-1,3-cyclopentane).

DOI： 10.1021/om971099u

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press  

This article deals with the rare earth metal initiated living polymerization of polar and nonpolar monomers to give monodisperse high molecular weight polymers at high conversion. A typical example is seen in the polymerization of methyl methacrylate with [SmH(C5Me5)2]2 or LnMe(C5Me5)2 (THF)] (Ln=Sm,Y, and Lu), giving high molecular weight syndiotactic polymers (Mn &gt
500,000, syndiotacticity &gt
95%) quantitatively at low temperature (-95°C). Synthesis of high molecular weight isotactic poly(MMA) with very low polydispercity was also achieved by the efficient catalytic action of [(SiMe3)3C]2Yb. Living polymerizations of alkyl acrylates were successfully carried out by the excellent catalysis of LnMe(C5Me5)2(THF) (Ln=Sm and Y). By taking advantages of the living polymerization ability, we attemted the ABA triblock copolymerization of MMA/butyl acrylate/MMA to obtain rubber-like elastic polymers. Organo rare earth metal complexes such as LnOR(C5R5)2 or LnR(C5R5)2 (Ln = Sm and Y, R = Me) conducted the living polymerizations of various lactones such as β-propiolactone, δ-valerolactone and ε-caprolactone, and also conducted the block copolymerizations of methyl methacrylate with various lactones. C1 symmetric bulky organolanthanide(III) complexes such as SiMe2[2(3),4-(SiMe)2C5H2] 2LnCH(SiMe3)2 (Ln = La, Sm, and Y) show high catalytic activity for linear polymerization of ethylene. Organolanthanide(II) complexes such as racemic SiMe2[2-SiMe3-4-tBu-C5H2] 2Sm(THF) as well as C1 symmetric SiMe2[2(3),4-(SiMe3)2C5H 2]2Sm(THF) were found to show high catalytic activity for the polymerization of ethylene, giving Mn &gt
106 with Mw/Mn = 1.6. Utilyzing the high polymerization activity of rare earth metal complexes towards both polar and nonpolar monomers, block copolymerizastions of ethylene with polar monomers such as methyl methacrylate and lactones were realized for the first time.

DOI： 10.1021/bk-1998-0704.ch011

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Language：Japanese   Publisher：THE SOCIRETY OF RUBBER SCIENCE AND TECHNOLOGYY, JAPAN  

DOI： 10.2324/gomu.70.91

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MARCEL DEKKER INC  

Organolanthanide(III) initiated polymerization of methyl methacryate gave both syndiotactic and isotactic living polymers of high molecular weight. Organolanthanide(III) initiated polymerization of alkyl acrylates also gave high molecular weight poly(alkyl acrylate)s with very narrow molecular weight distribuion in high yield. Molecular weights of the resulting polymers increased linearly with the conversion. Random and block copolymerizations of alkyl acrylates with methyl methacrylate were realized successfully. For the sake of development of the olefin polymerization catalyst, bulky substituents were introduced into Me2Si bridged Cp rings and they were used as ligands for the lanthanide complexes. Tri-and divalent lanthanide complexes with such ligands showed high activity for olefin polymerization and gave high molecular weight polyolefins.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

A nonmetallocene-type rare earth metal complex, [(SiMe3)(3)C](2)Yb, was found to proceed the isotactic polymerization of methyl methacrylate (MMA) to give a high molecular weight polymer with narrow molecular weight distribution. We can synthesize stereo-complexes of poly(MMA) by mixing the resulting isotactic polymer with the high molecular weight syndiotactic poly(MMA) synthesized with SmH(C5Me5)(2). Half-sandwich type rare earth metal complex, (C3Me3)La[CH(SiMe3)(2)](2), proceeds the polymerization of styrene, alkyl isocyanates, acrylonitrile, and ethylene. Furthermore, rare earth metal complexes exhibiting one cyclopentadienyl group and one acetylene group or benzyl group also showed relatively large catalytic activity for the polymerization of ethylene. A novel triphenyl complex, (2,6-alkoxy C6H3)(3)Sm, was also prepared but this complex showed very weak catalytic activity towards the polymerization of ethylene.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Ethylene polymerization was explored by using the racemic SiMe(2)(2-SiMe(3)-4-tBuC(5)H(2))(2)Sm(THF)(2) complex (1), meso type Me(2)Si(Me(2)SiOSiMe(2))(3-tBuC(5)H(2))(2)Sm(THF)(2) complex (2), and C-1-symmetric SiMe(2)[2,4-(SiMe(3))(2)C5H2][3,4-(SiMe(3))(2)C5H2]Sm(THF)2 complex (3) in the absence of methylaluminoxane. As a result, the mese isomer exhibits highest initiating activity, but the number-average molecular weight is relatively low ((M) over bar(n) = 50000). In contrast to these complexes, the C-1-symmetric complex provides the highest molecular weight of polyethylene, (M) over bar(n) &gt; 1000000, with relatively narrow molecular weight distribution ((M) over bar(w)/(M) over bar(n) = 1.60). Only the racemic complex exhibits good activity for the polymerization of propylene, 1-pentene and 1-hexene.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Organolanthanide complexes such as SmMe(C(5)Me(5))(2)(THF) and [SmH(C(5)M(5))(2)](2) initiate the living polymerizations of epsilon-caprolactone and delta-valerolactone to give high molecular weight polyesters (M(n) &gt; 70 000) with extremely narrow molecular weight distributions, M(w)/M(n) &lt; 1.08, while these initiators are completely inert for the polymerization of beta-propiolactone. In contrast to lanthanide alkyl complexes, lanthanide alkoxides such as SmOEt(C(5)Me(5))(2)(OEt(2)), [YOMe(C5H5)(2)](2), and YOMe(C(5)Me(5))(2)(THF) exhibit fairly good catalytic activity for polymerizations of beta-propiolactone, delta-valerolactone, and epsilon-caprolactone. The initiation mechanisms for the polymerization of lactones by LnMe(C(5)Me(5))(2)(THF) (Ln = Sm, Yb) or LnOR(C(5)R'(5))(2) (Ln = Sm, Y) initiators are discussed on the basis of equimolar reactions between organolanthanides and lactones.

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Language：Japanese   Publisher：The Crystallographic Society of Japan  

DOI： 10.5940/jcrsj.38.Supplement_75

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Rare earth metal complexes such as SmMe(C(5)Me(5)2)(THF) or YMe(C(5)Me(5))(2)(THF) (THF = tetrahydrofuran) catalyze the living polymerization of alkyl acrylates (alkyl = methyl (Me), ethyl (Et), n-butyl (nBu), tert-butyl (tBu)) to give high molecular weight polymers, with extremely narrow molecular weight distributions, in high conversion. Random living copolymerization of methyl acrylate with n-butyl acrylate was successful by the effective catalytic action of SmMe(C(5)Me(5))(2)(THF). By taking advantage of the living polymerization of alkyl acrylates and alkyl methacrylates, a triblock copolymer of methyl methacrylate/n-butyl acrylate/methyl methacrylate was prepared, and the resulting polymer exhibited good elastic properties. In particular, an 8:72:20 copolymer had an ultimate elongation of 163% and compression set of 58%. Block copolymerizations of alkyl acrylates with lactones gave lactone rich copolymers with narrow molecular weight distributions.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS LTD  

Methyl methacrylate (MMA) oligomers (M(n) similar or equal to 2500) with a narrow molecular weight distribution (M(w)/M(n) &lt; 1.10) were synthesized by using a Cp*(2)SmMe(THF) initiator (Co=eta-C). The oligomerization proceeds via a samarium enolate as the propagating species and the reaction of the living oligomer with p-tolualdehyde produced p-tolyl hydroxymethyl-terminated oligoMMA.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Sterically bulky substituents, t-BuMe(2)Si groups, and Me(3)Si groups were introduced into Me(2)Si bridged Cp rings and the compound, Me(2)Si(Me(3)Si-t-BuC(5)H(3))(2), was used asa ligand for rare earth metal complex. As a result of the complexation, new yttrium complexes, Me(2)Si(2-Me(3)Si-(4)-t-BuMe(2)SiC(5)H(2))(2)YCl2Li(THF)(2) and Me(2)Si((2)-Me(3)Si-4-t-BuMe(2)SiC(5)H(2))(2)YCH(SiMe(3))(2), were synthesized. Hydride derivative of these complexes, [Me(2)Si((2)-Me(3)Si-4-t-BuMe(2)SiC(5)H(2))(2)YH](2), showed high activity for olefin polymerization. alpha-Olefins such as l-hexene and I-pentene were transformed into their polymers in high yield (&gt;75%). The polymerization proceeded in a stereoselective manner, giving highly isotactic poly(alpha-olefin)s (selectivity&gt;95%). The hydride complex can polymerize 1,5-hexadiene, affording high molecular weight poly(methylene-1,3-cyclopentane) (Mn&gt;10x10(4)).

DOI： 10.1016/0040-4020(94)01141-L

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Language：Japanese   Publisher：The Crystallographic Society of Japan  

DOI： 10.5940/jcrsj.36.Supplement_92

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：VCH PUBLISHERS INC  

The helical pentamer 1, active in polymerizations, was obtained from the appropriate 1,2-diisocyanoarene and the chiral Pd complex trans-[PdBr(CH3)L2*]. With diastereomerically pure 1 as the polymerization initiator helical polyquinoxalinediyls can be prepared enantioselectively from 1,2-diisocyanoarene, L* = PPh[(S)-2-methylbutyl]2.

DOI： 10.1002/anie.199215091

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Ring-opening polymerization of 2-methyl-2-oxazoline followed by termination with 3-aminopropyltriethoxysilane produced poly(N-acetylethylenimine) (polyoxazoline) (POZO) having a terminal triethoxysilyl group. Triethoxysilyl-terminated telechelic POZO was also prepared by using bifunctional initiators. These silane coupling POZOs were subjected to reaction with silanol groups at the surface of silica gel to modify its surface hydrophilicity. Triethoxysilyl-terminated POZOs were also subjected to acid-catalyzed cohydrolysis polymerization with tetraethoxysilane by the so-called sol-gel method to produce a novel organic-inorganic hybrid polymer (block copolymer). The hybrid obtained was a homogeneous, transparent, glassy composite material, which showed more hydrophilicity in comparison with that of silica gel without POZO segments. On the other hand, a hybrid polymer consisting of poly(2-ethyl-2-oxazoline) and silica gel showed amphiphilic properties absorbing both water and organic solvents. Pyrolysis of these hybrids at 600-degrees-C produced silica having micro-pores.

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Language：English   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ja00173a070

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

DOI： 10.1039/c39900000403

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ma00195a003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER VERLAG  

DOI： 10.1007/BF00263911

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Language：Japanese   Publishing type：Book review, literature introduction, etc.   Publisher：SOC SYNTHETIC ORGANIC CHEM JPN  

Poly(substituted methylene) synthesis (PSMS) is a method for preparing carbon-carbon main chain polymers, where the main chain is constructed from one carbon unit. If we can find monomers and initiators suitable for the process, PSMS could be a powerful tool for polymer synthesis, providing a method for preparing C-C main chain polymers which cannot be obtained by vinyl polymerization. This review describes recent development for PSMS, particularly focusing on transition metal initiated polymerization of diazocarbonyl compounds, which can afford polymers bearing polar substituents such as ester and acyl groups on all the main chain carbons. A variety of poly (substituted methylene)s can be prepared by Pd-mediated (co)polymerization of the monomers with various substituents on their carbonyl carbons, although the molecular weights of the products are a few thousands. Pd-mediated and thermally-induced copolymerizations of diazocarbonyl compounds with alkynes and styrene, respectively, are also possible. On the other hand, Rh-mediated polymerization of ethyl diazoacetate proceeds in a highly stereospecific manner, giving syndiotactic poly (ethoxycarbonyl methylene)s with high molecular weights (M-n &gt; 100000).

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Language：Japanese   Publisher：高分子刊行会  

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Language：Japanese   Publisher：化学同人  

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Language：Japanese   Publisher：日産科学振興財団  

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Language：English   Publishing type：Book review, literature introduction, etc.   Publisher：SOC SYNTHETIC ORGANIC CHEM JPN  

New approaches to organo-transition-metal catalyzed-polymerizations of methyl methacrylate (MMA), ethylene, and 1-olefins using modified methylalumoxane (MMAO) as cocatalyst are described. Ni(acac)(2), (C5H5)Ni(eta (3)-C3H5), [NiMe4Li2(THF)(2)](2) coupled with MMAO showed a good catalytic activity toward the polymerization of MMA. A variety of (C5R5)Pd(eta (3)-C3H5) also showed good catalytic activities for the polymerization of MMA, while these initiators exhibited no catalysis for the polymerizations of ethylene and 1-olefins. V(1-R,3-R'-acac)(3)/MMAO systems showed a moderate catalytic activity for the polymerization of ethylene, while the polymerization using (2-dimethylaminoethyl-C5Me4)VCl2 produced high-molecular-weight polyethylenes. [6-Thiobis(2,4-di-tert-butyl-phenolate)]VOCl2, and (N,N'-ditert-butyl-1,1'-binaphthyl-2,2'-diamino) VOCl2 exhibited a higher catalytic activity for the polymerization of ethylene. The (Ind)CH2CH2NMe2CrCl2/MMAO system also showed a high catalytic activity. Me2Si bridged lanthanocene complexes showed high catalytic activity for both block copolymerizations of ethylene with polar monomers such as MMA or epsilon -caprolactone and the block copolymerizations of 1-hexene with polar monomers.

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Book review, literature introduction, etc.   Publisher：CHEMICAL SOC JAPAN  

This review article deals with the rare earth metal initiated polymerization of polar and nonpolar monomers in living fashion (''living'' means very active without termination and chain transfer reaction) to give monodisperse high molecular weight polymers at high conversion. A typical example is seen in the polymerization of methyl methacrylate with [SmH(C5Me5)(2)](2) or [LnMe(C5Me5)(2)(THF)] (Ln = Sm, Y, and Lu), giving high molecular weight syndiotactic polymers (M-n &gt; 500000, syndiotacticity &gt; 95%) quantitatively at low temperature (-95 degrees C). The initiation mechanism was discussed on the basis of X-ray analysis of the 1 : 2 adduct (molar ratio) of [SmH(C5Me5)(2)]2 with MMA. Living polymerizations of alkyl acrylates (methyl acrylate, ethyl acrylate, and butyl acrylate) were also possible by the catalysis of [LnMe(C5Me5)(2)(THF)] (Ln=Sm, Y); i.e. poly(methyl acrylate) M-n=48x1O(3), M-w/M-n=1.04, poly(ethyl acrylate) M-n=55x10(3), M-w/M-n=1.04, and poly(butyl acrylate) M-n = 70 x 10(3), M-w/M-n = 1.05. By taking advantages of the living polymerization ability, we attempted ABA triblock copolymerization of MMA/butyl acrylate/MMA to obtain rubber-like elastic polymers. Lanthanum alkoxide(III) has good catalytic activity for the polymerization of alkyl isocyanates (M-n &gt; 10(6), M-w/M-n = 2.08). Monodisperse polymerizations of lactones, lactide, and various oxiranes were also achieved by polymerization with rare earth metal complexes. C-1 symmetric bulky organolanthanide(III) complexes such as {SiMe2[2(3),4-(SiMe)(2)C5H2](2)LnCH(SiMe3)(2)} (Ln = La, Sm, and Y) show high activity for linear polymerization of ethylene. Organolanthanide( complexes such as racemic (SiMe2[2-SiMe3-4-tBu-C5H2](2)Sm(THF) as well as C-1 symmetric{SiMe2[2(3),4-(SiMe3)(2)C5H2](2)Sm(THF)} were also found to have high activity for the polymerization of ethylene. Thus, polyethylene of M-n &gt; 10(6) (M-w/M-n = 1.6) was first obtained by using {SiMe2[2(3),4-(SiMe3)(2)C5H2](2)Sm(THF)}. 1,4-Cis conjugated diene polymerization of 1,3-butadiene and isoprene became available by the efficient catalytic activity of NdCl(C5H5)(2)/AlR3 or Nd(octanoate)(3)/AlR3. The Ln(naphthenate)(3)/AliBu(3) system allows selective polymerization of acetylene in cia-fashion. Utilyzing the fact that rare earth metal initiated living polymerization proceeds for both polar and nonpolar monomers, researchers have attempted to block copolymerization of ethylene with MMA or lactones yielding polyethylene derivatives having high chemical reactivity.

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CiNii Books

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Book review, literature introduction, etc.   Publisher：SPRINGER-VERLAG BERLIN  

This review article shows that by using the versatile functions of rare earth metal complexes we can polymerize both polar and nonpolar monomers in living fashion to obtain monodisperse high molecular weight polymers at high conversions. A typical example is the polymerization of methyl methacrylate with [SmH(C5Me5)(2)](2), or LnMe(C5Me5)(2) (THF) (Ln = Sm, Y, Lu), which leads quantitatively to high molecular weight syndiotactic polymers (M-n &gt; 500000, syndiotacticity &gt; 95%) at low temperature (-95 degrees C). The initiation mechanism was discussed on the basis of X-ray analysis of the 1:2 adduct (molar ratio) of [SmH(C5Me5)(2)](2) with MMA. Living polymerizations of alkyl acrylates (methyl acrylate, ethyl acrylate, butyl acrylate) were also made possible by using LnMe(C5Me5)(2)(THF) (Ln = Sm, Y), with the results: poly(methyl acrylate) M-n = 48 x 10(3), M-w/M-n = 1.04, poly(ethyl acrylate) M-n = 55x10(3), M-w/M-n = 1.04, and poly(butyl acrylate) M-n = 70x10(3), M-w/M-n = 1.05. By taking advantage of the ABA triblock copolymerization of MMA/butyl acrylate/MMA, it was possible to obtain rubberlike elastic polymers. Lanthanum alkoxide(III) has good catalytic activity for the polymerization of alkylisocyanates (M-n&gt;10(6), M-w/M-n = 2.08). Monodisperse polymerization of lactones, lactide, and oxirane was also achieved by polymerization with rare earth metal complexes. C-1 symmetric bulky organolanthanide(III) complexes such as SiMe2[2(3),4-(SiMe3)(2)C5H2](2) LnCH(SiMe3)(2) (Ln = La, Sm, Y) show high activity for linear polymerization of ethylene. Organolanthanide(II)(II) complexes such as racemic SiMe2 [2-SiMe3-4-tBu-C5H2](2) Sm(THF)(2) as well as C-1 symmetric SiMe2 [2(3),4-(SiMe3)(2)C5H2](2) Sm(THF)2 were also found to have a very high activity for polymerization of ethylene. Thus, polyethylene of M-n &gt; 10(6) (M-w/M-n = 1.60) was obtained by using SiMe2[2(3),4-(SiMe3)(2)C5H2](2) Sm(THF)(2). 1,4-cis Conjugated diene polymers of butadiene and isoprene became available by the efficient catalytic activity of C5H5NdCl/AIR(3) or Nd(octanoate)(3)/AIR(3). The Ln(naphthenate)(3)/ AliBu(3) system allows selective polymerization of acetylene in cis fashion to take place at high yield. Considering the fact that rare earth metal-initiated living polymerization can be achieved for both polar and nonpolar monomers, attempts have been made to block copolymerization of ethylene with MMA or lactones yielding polyethylene derivatives having high chemical reactivity.

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DOI： 10.1295/koron.54.641

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Language：English   Publisher：HUTHIG & WEPF VERLAG  

Organolanthanide(III) initiated polymerizations of alkyl methacrylates and alkyl acrylates proceed in a living fashion and yield high molecular weight polymers with extremely narrow molecular weight distribution at high conversion. Random and block copolymerizations of alkyl acrylates are carried out successfully to give almost ''monodisperse'' polymers. Rare earth metal initiated polymerizations of lactones such as epsilon-caprolactone and delta-valerolactone produce again high molecular weight polymers with narrow molecular weight distribution. Bulky divalent and trivalent rare earth metal complexes catalyze the living polymerization of ethylene and alpha-olefins and the Sm(OR)(3)/AlR(3)-H2O initiator system catalyzes the polymerization of propylene oxide to give polymers with narrow molecular weight distribution.

DOI： 10.1002/macp.1995.021960802

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Language：English   Publisher：HUTHIG & WEPF VERLAG  

Organolanthanide (III) initiated polymerization of alkyl acrylates gave high molecular weight poly(alkyl acrylate)s with extremely narrow molecular weight distribution in high yield. Molecular weight of the polymers increased linearly with the conversion. Random and block copolymerizations of acrylate monomers (alkyl acrylates and MMA) were successful. For development of olefin polymerization catalystsbased on lanthanide complexes, bulky substituents were introduced into Me(2)Si bridged Cp rings and they were used as ligands of lanthanide complexes. Tri- and divalent lanthanide complexes with such a ligand system showed high activity for olefin polymerization and gave high molecular weight polyolefins.

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Language：English   Publisher：JAPAN ACAD  

Rare earth metal complexes such as SmMe(C(5)Me(5))(2)(THF) or YMe(C(5)Me(5))(2)(THF) catalyze the living polymerization of alkyl acrylates (alkyl=Me, Et, nBu, tBu) to give high molecular weight polymers with extremely low polydispersity in high conversion. Random living copolymerization of methyl acrylate with butyl acrylate was also successful by the catalytic action of SmMe(C(5)Me(5))(2)(THF). By taking advantage of the living polymerization ability of alkyl acrylates and alkyl methacrylates, a triblock copolymerization of methyl methacrylate/butyl acrylate/methyl methacrylate was performed to find rubber-like elastic propel-ties. As a result, 8:72:20 block-copolymer was found to exhibit the desired elastic character, which showed the elongation properties of 163% and compression set of 58%.

DOI： 10.2183/pjab.71.126

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Language：Japanese   Publisher：高分子学会  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publisher：ELSEVIER SCIENCE PUBL B V  

High molecular weight polyethylene (M(n) &gt; 300,000, M(w)/M(n) = 1.6) was obtained by using bulky Sm(II) or Sm(III) species such as Me(2)Si(2-SiMe(3)-4-tBu-C5H2)(2))Sm(THF) and Me(2)Si[2(3),4-(SiMe(3))(2)-C5H2]2SmCH(SiMe(3))(2) as initiator. These complexes also conduct the polymerization of l-pentene and 1-hexene to give isotactic polymers of Mn &gt; 20,000 with M(w)/M(n) = 1.6. By contrast the polar monomers such as methyl methacrylate and alkyl acrylates also proceeded the living polymerization by using Ln(C(5)Me(5))(2)R (R = H, Me) to give high molecular weight polymers (M(n) &gt; 450,000) with extremely low polydispersity (M(w)/M(n) &lt; 1.05).

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Publisher：The Society of Polymer Science, Japan  

DOI： 10.1295/kobunshi.43.534

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Other Link： https://jlc.jst.go.jp/DN/JALC/00382748071?from=CiNii

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Recent developments of olefin polymerization catalysts based on group III and IV metal complexes are described. Me2Si-bridged Cp rings with sterically bulky substituents were used as ligands for organolanthanide complexes and their reactivities to olefins were examined. As for the divalent Sm, racemic type complex Me2Si(2-Me3Si-4-t-Bu-C5H2)2Sm (THF)2 gave higher molecular weight polyethylene than Cp*2Sm(THF)2, and also showed catalytic activity to a-olefins. giving isotactic poly(a-olefin)s. A meso type Sm(II) complex with high activity for ethylene polymerization afforded relatively low molecular weight polyethylene. A C1 symmetric trivalent Sm complex Me2Si[2, 4-(Me3Si)2C5H2] [3, 4-(Me3 Si)2C5H2]SmCH(SiMe3)2 showed high activity for ethylene polymerization, but the same kinds of racemic and meso type complexes did not show it at all. The structures of the active complexes were revealed by the X-ray method. Atrivalent hydride complex [Me2Si(2-Me3Si-4-t-BuMe2Si-C5H2)2H]2 showed high activity for a-olefins, giving isotactic poly(l-pentene) and poly(l-hexene) in high yield. Furthermore, the complex catalyzed cyclopolymerization of 1, 5-hexadiene affording high molecular weight poly (methylene-1, 3-cyclopentane). © 1994, The Society of Polymer Science, Japan. All rights reserved.

DOI： 10.1295/koron.51.637

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Language：English   Publisher：ELSEVIER SCIENCE PUBL B V  

High molecular weight polyethylene (M(n) &gt; 300,000, M(w)/M(n) = 1.6) was obtained by using bulky Sm(II) or Sm(III) species such as Me(2)Si(2-SiMe(3)-4-tBu-C5H2)(2))Sm(THF) and Me(2)Si[2(3),4-(SiMe(3))(2)-C5H2]2SmCH(SiMe(3))(2) as initiator. These complexes also conduct the polymerization of l-pentene and 1-hexene to give isotactic polymers of Mn &gt; 20,000 with M(w)/M(n) = 1.6. By contrast the polar monomers such as methyl methacrylate and alkyl acrylates also proceeded the living polymerization by using Ln(C(5)Me(5))(2)R (R = H, Me) to give high molecular weight polymers (M(n) &gt; 450,000) with extremely low polydispersity (M(w)/M(n) &lt; 1.05).

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Polyoxazoline having a terminal triethoxysilyl group was successfully synthesized by the ring-opening polymerization of 2-methyl-2-oxazoline followed by termination with (3-aminopropyl)triethoxysilane. Triethoxysilyl-terminated telechelic polyoxazoline was prepared by using a bifunctional initiator. Furthermore, polyoxazolines having two or three triethoxysilyl groups were prepared by using diallylamine as a terminator followed by a hydrosilation reaction with triethoxysilane. These triethoxysilyl-terminated polyoxazolines were subjected to acid-catalyzed cohydrolysis polymerization with tetraethoxysilane by the so-called sol-gel method to produce a novel organic-inorganic polymer hybrid, which was a homogeneous transparent glassy composite material. The obtained hybrid showed a higher hydrophilic property in comparison with that of silica gel without polyoxazoline segments.

DOI： 10.1021/ma00073a023

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Language：Japanese   Publisher：SOC SYNTHETIC ORGANIC CHEM JPN  

Organometallics of rare earths such as (C5Me5)2LnR (Ln = Y, Sm, Yb, Lu; R = H, Me) initiated the living polymerizations of alkyl methacrylates and alkyl acrylates for the first time to afford high molecular weight polymers (M(n) &gt; 500, 000) with extremely narrow molecular weight distribution (M(w)/M(n) &lt; 1. 05). The 1 : 2 reaction of SmH(C5Me5), with MMA provides a single crystal and its X-ray analysis revealed the formation of an 8-membered ring complex where one end is bound with enolate form and the other end by the coordination of ester group of MMA. Based on these findings we propose coordination anionic polymerization mechanism for this reaction. SmMe(C5Me5)2(THF) and YOMe(C5Me5)2(THF) were also able to conduct the living polymerizations of beta-propiolactone, delta-valerolactone and epsilon-caprolactone. Organo rare earth metal (II) complex with bulky auxiliary ligand, Me2Si (2-Me3Si-4-tBu-C5H2)2Sm, as well as rare earth metal (III) complexes, Me2Si[2,4-(Me3Si)2C5H2]2LnCH(SiMe3)2 (Ln = La, Sm), were found to conduct the polymerization of ethylene to give high moleculr weight polymers with narrow molecular weigt distribution.

DOI： 10.5059/yukigoseikyokaishi.51.931

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Language：English   Publisher：AMER CHEMICAL SOC  

Polyoxazoline having a terminal triethoxysilyl group was successfully synthesized by the ring-opening polymerization of 2-methyl-2-oxazoline followed by termination with (3-aminopropyl)triethoxysilane. Triethoxysilyl-terminated telechelic polyoxazoline was prepared by using a bifunctional initiator. Furthermore, polyoxazolines having two or three triethoxysilyl groups were prepared by using diallylamine as a terminator followed by a hydrosilation reaction with triethoxysilane. These triethoxysilyl-terminated polyoxazolines were subjected to acid-catalyzed cohydrolysis polymerization with tetraethoxysilane by the so-called sol-gel method to produce a novel organic-inorganic polymer hybrid, which was a homogeneous transparent glassy composite material. The obtained hybrid showed a higher hydrophilic property in comparison with that of silica gel without polyoxazoline segments.

DOI： 10.1021/ma00073a023

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Language：English   Publisher：SPRINGER VERLAG  

Ring-opening polymerization of 2-alkyl-2-oxazoline (alkyl=ethyl, n-butyl, n-octyl) was carried out with an initiator of methyl tosylate followed by the treatment with 3-aminopropyltriethoxysilane to produce a novel type of polymeric silane coupling agents. Similarly, telechelic triethoxysilyl-terminated poly(2-alkyl-2-oxazoline)s were prepared by using a bifunctional initiator. The molecular weights of the produced polymers could be effectively controlled by the feed ratio of the initiator to the monomer. These end-functionalized polymers were reacted with tetraethoxysilane with an acid catalyst by the sol-gel method. In the case of poly(2-ethyl-2-oxazoline), a homogeneous and transparent polymer hybrid was obtained. This polymer hybrid absorbed both of water and organic solvents, which showed amphiphilic adsorption property.

DOI： 10.1007/BF00692958

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Language：English   Publisher：SPRINGER VERLAG  

Ring-opening polymerization of 2-alkyl-2-oxazoline (alkyl=ethyl, n-butyl, n-octyl) was carried out with an initiator of methyl tosylate followed by the treatment with 3-aminopropyltriethoxysilane to produce a novel type of polymeric silane coupling agents. Similarly, telechelic triethoxysilyl-terminated poly(2-alkyl-2-oxazoline)s were prepared by using a bifunctional initiator. The molecular weights of the produced polymers could be effectively controlled by the feed ratio of the initiator to the monomer. These end-functionalized polymers were reacted with tetraethoxysilane with an acid catalyst by the sol-gel method. In the case of poly(2-ethyl-2-oxazoline), a homogeneous and transparent polymer hybrid was obtained. This polymer hybrid absorbed both of water and organic solvents, which showed amphiphilic adsorption property.

DOI： 10.1007/BF00692958

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Language：English   Publisher：SPRINGER VERLAG  

Telechelic bifunctional polyoxazoline (poly(N-acetylethylenimine), PAEI) was prepared by ring-opening polymerization of 2-methyl-2-oxazoline (1) in the presence of p-(alpha,alpha'-dibromo)xylene (2) as an initiator. The terminal propagating ends of this polyoxazoline were reacted with 3-aminopropyltrimethoxysilane (4) to give telechelic trimethoxysilyl-terminated polyoxazoline (5). Gelation of this telechelic polymer was carried out by hydrolysis and condensation of alkoxysilyl groups. By this method, the PAEI gels were obtained in good yields, and their degrees of swelling in the solvent could be controlled successfully by the feed ratios of the initiator to the monomer in the stage of the polymerization of 2-methyl-2-oxazoline. However, the cross-linked products were not stable and gradually dissolved in water. The gels were also swollen in N,N-dimethylformamide (DMF). The degrees of swelling of these gels were thus measured in DMF.

DOI： 10.1007/BF00692957

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Language：English   Publisher：SPRINGER VERLAG  

Telechelic bifunctional polyoxazoline (poly(N-acetylethylenimine), PAEI) was prepared by ring-opening polymerization of 2-methyl-2-oxazoline (1) in the presence of p-(alpha,alpha'-dibromo)xylene (2) as an initiator. The terminal propagating ends of this polyoxazoline were reacted with 3-aminopropyltrimethoxysilane (4) to give telechelic trimethoxysilyl-terminated polyoxazoline (5). Gelation of this telechelic polymer was carried out by hydrolysis and condensation of alkoxysilyl groups. By this method, the PAEI gels were obtained in good yields, and their degrees of swelling in the solvent could be controlled successfully by the feed ratios of the initiator to the monomer in the stage of the polymerization of 2-methyl-2-oxazoline. However, the cross-linked products were not stable and gradually dissolved in water. The gels were also swollen in N,N-dimethylformamide (DMF). The degrees of swelling of these gels were thus measured in DMF.

DOI： 10.1007/BF00692957

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DOI： 10.5059/yukigoseikyokaishi.51.931

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Language：Japanese   Publisher：化学工業社  

CiNii Books

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Language：Japanese   Publisher：THE SOCIRETY OF RUBBER SCIENCE AND TECHNOLOGYY, JAPAN  

DOI： 10.2324/gomu.66.612

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00022562517?from=CiNii

Language：English   Publisher：AMER CHEMICAL SOC  

Empirical conformational energy calculations were performed on helical poly (2,3-quinoxaline)s to predict stable conformations. Two energy minimum conformations were found by varying the dihedral angle (psi) between two adjacent quinoxaline units from 5 to 180-degrees. Circular dichroism (CD) spectra were calculated for the two stable conformations (psi = 45 and 135-degrees) on the basis of exciton theory. The experimental CD spectrum of (+)-poly(2,3-quinoxaline) was in accord with the theoretical spectrum for a right-handed helical conformation with a dihedral angle of 135-degrees.

DOI： 10.1021/ma00051a013

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Language：English   Publisher：AMER CHEMICAL SOC  

Empirical conformational energy calculations were performed on helical poly (2,3-quinoxaline)s to predict stable conformations. Two energy minimum conformations were found by varying the dihedral angle (psi) between two adjacent quinoxaline units from 5 to 180-degrees. Circular dichroism (CD) spectra were calculated for the two stable conformations (psi = 45 and 135-degrees) on the basis of exciton theory. The experimental CD spectrum of (+)-poly(2,3-quinoxaline) was in accord with the theoretical spectrum for a right-handed helical conformation with a dihedral angle of 135-degrees.

DOI： 10.1021/ma00051a013

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ma00050a050

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ma00050a050

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DOI： 10.1002/anie.199215091

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

Polyoxazoline-polysiloxane-polyoxazoline (ABA type) block copolymers were prepared. Amino-terminated telechelic poly(dimethylsiloxane)s were obtained by ring-opening equilibrium polymerization of octamethylcyclotetrasiloxane in the presence of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and tetramethylaminonium hydroxide as an end blocker and a catalyst, respectively. Propagating oxazolinium species at the end of poly(2-methyl-2-oxazoline)s were reacted with amino groups of the ends of polysiloxanes to give polyoxazoline-polysiloxane block copolymers.

DOI： 10.1295/koron.49.943

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Language：English  

Polyoxazoline-polysiloxane-polyoxazoline (ABA type) block copolymers were prepared. Amino-terminated telechelic poly(dimethylsiloxane)s were obtained by ring-opening equilibrium polymerization of octamethylcyclotet-rasiloxane in the presence of l,3-bis(3-aminopropyl)tetramethyldisiloxane and tetramethylammonium hydroxide as an end blocker and a catalyst, respectively. Propagating oxazolinium species at the end of poly(2-methyl-2-oxazoline)s were reacts with amino groups of the ends of polysiloxanes to give polyoxazoline-polysiloxane block copolymers. © 1992, The Society of Polymer Science, Japan. All rights reserved.

DOI： 10.1295/koron.49.943

Scopus

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

DOI： 10.1295/polymj.24.297

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

DOI： 10.1295/polymj.24.297

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DOI： 10.1002/anie.199215091

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Language：English   Publisher：AMER CHEMICAL SOC  

We report here a polyaddition between diene and monoalkylborane, that is, "Hydroboration Polymerization". The reaction of thexylborane with 1,7-octadiene was carried out in tetrahydrofuran at 0-degrees-C under nitrogen atmosphere to produce an organoboron polymer. The molecular weight of the polymer obtained increased as the feed ratio to unity was approached. As a diene component, 1,9-decadiene, p-divinylbenzene, p-diallylbenzene, bis(allyl ether)s of ethylene glycol, 1,4-butanediol, triethylene glycol, hydroquinone, and bisphenol A were used in this hydroboration polymerization to give the corresponding organoboron polymers. The thermal and oxidative stabilities of the obtained polymers were examined. These polymers were a little more stable toward air in comparison with conventional "trialkylboranes".

DOI： 10.1021/ma00002a001

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Language：English   Publisher：AMER CHEMICAL SOC  

We report here a polyaddition between diene and monoalkylborane, that is, "Hydroboration Polymerization". The reaction of thexylborane with 1,7-octadiene was carried out in tetrahydrofuran at 0-degrees-C under nitrogen atmosphere to produce an organoboron polymer. The molecular weight of the polymer obtained increased as the feed ratio to unity was approached. As a diene component, 1,9-decadiene, p-divinylbenzene, p-diallylbenzene, bis(allyl ether)s of ethylene glycol, 1,4-butanediol, triethylene glycol, hydroquinone, and bisphenol A were used in this hydroboration polymerization to give the corresponding organoboron polymers. The thermal and oxidative stabilities of the obtained polymers were examined. These polymers were a little more stable toward air in comparison with conventional "trialkylboranes".

DOI： 10.1021/ma00002a001

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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DOI： 10.1021/ma00208a006

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Language：English   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ma00208a006

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Venue：札幌コンベンションセンター  

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Venue：京都大学桂キャンパス  

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